Obviously, this work is not the be all and end all of low magic campaigning.  Really, it only answers one question.
        "What kind of rewards do you give players other than magical items?"
        Now, there's all the standard responses... titles... land... public recognition...
        That's all well and good, but at some point that's just not good enough.  Getting another plot of land and 20 serfs can get just as boring as getting another two thousand gold.

        So basically, I made two tables while I was supposed to be programming last night.  You can roll on them, I guess, but its usually better to choose them for yourself.

Special Weapons in a Low Magic Realm (1d20)
1-3
Plus one to hit.  Is exceptionally well balanced.  I'd expect to see these on a thief or assassin.  Generally made for a specific person.  Someone far enough away from that person's body type or fighting style is likely not to get the bonus.
4-6
Pentrates one level of armor.  A classic type of weapon advancement.  Basically provides a +1 to hit against armored opponents.  A more realistic track would be to select a certain type of armor for it to have a +1 against (chain mail, plate mail, leathers)
7-8
Plus one to damage.  More weighty (perhaps requiring higher strength to use effectively) or very sharp.  More likely in areas were armor is minimal.
9-10
Subrtract one from initiative (if you use it).  Light and whippy.  Probably made from a higher grade steel making it significantly lighter while maintaining the same strength.  Brings to mind rapiers.
11-12
Masterful weapon.  Plus one to hit and damage.  Probably very easy to identify (I'd give anyone with proficency in the weapon an Int Check +2).  Will almost certainly have a smithers mark.  Having a few names written down for the identities of these smiths is a nice touch for a campaign (they're likely not more than two or three alive in the campaign area, maybe less).
13-15
Resilient.  This weapon was made to last through the generations.  It is +2 to all item saving throws.  Item saves don't come up too much in most campaigns, but probably should more often.  Especially in low magic campaigns.  When you get hit by that first fireball, you know.
16-17
Made of a strange material.  Perhaps its obsidian (better than iron against lowly armored opponents, but doesn't stand up to stress), flint (ancient relic?), or some precious metal (decretive piece or superstition).  There may be some bonuses or penalties, but the main idea is flavor.  In higher magic campaigns things like elven steel, adamant(ine, ite), and dragon bone (a personal fave) come to mind.
18
Blessed.  This item is the weapon of a certain faith.  It acts as a minor magical weapon for them, and simply a normal weapon for everyone else.  Usually, adventurers get these by taking out religous agents, but blessed items can turn up in the strangest places.
19
Lucky.  Its not magic (to detection), but strange things happen around it or are rumored to happen around it.  Give the weapon a long/short, colorful history.  Make it distinctive.  Attatch a prophecy (or two or three) to it.  Whether or not it really is magical or the rumors are true, you've probably dragged the players through a merry chase.  A lot of experienced players will automatically jump to the conclusion that its an artifact or relic.  This is one of those opertunities to be smug.
20
An actual honest to god magical item.  Remember to twist it though.
    Give it shocking grasp 1/day,
    Have the angry spirits of the slain follow the player,
    Have it attract a certain race of monster or creature (a druid in one of my campaigns got truly paranoid about all the squirrels following her until she figured out they were just attracted to her staff),
    Have its bonus fluctuate on the basis of the morality of the deed its being used for (killing tyrants +3, killing innocents -3),
    Have it drain the users hit points to power it in battle,
    Have it jynx the characters compatriots,
    It randomly uses the spell Babble,
    It prevents the wielder's wounds from becoming scars,
Anything that strikes your fancy.  Just remember not to tell the players right away if they wouldn't know.  I know that personally, I never let an item get out of my sight that doesn't have some strange little quirk to it.  Some items in the DMG rule, but most of them are kind of bland.  Make them think, they'll thank you for it (well, they should).

Every magical item deserves a history in a Low Magic Campaign.  EVERY item.  Sometimes, your players won't know about it, but before you give out an item think up its past.  Just a few notes jotted down (or in your head).  If you get tired of thinking up histories, you're giving out too many items.  High Magic is a little different, obviously.  In High Magic it only applies to the more potent items.  Remember, that potion of heroism contains the ground heart of the hero of K'tai Pass.  How will that effect the PC while under its influence?  It helps make magic magical again, moreso than just restricting its access ever could.

Special Armor in Low Magic Campaigns
1-5
Highly decorative.  Is worth much more than the base simply on the value of its artistry.  This armor was probably part of the guard of some king or cheiftan.  Watch them squirm when every hit their armor absorbs takes ten gold out of its value.  Make it the best armor they've found and this can give them a real moral dilemma.
6-9
Made to last.  Much like weapons, some armors are made to survive hell and high water.  This armor will not rust, melt, or otherwise degrade under anything like normal conditions.  It gains +2 to item saves and will last through even the most prolonged battles.
10-11
Expertly crafted.  Grants a +1 bonus to AC without adding weight.  Probably looks really nice too.  Like weapons, this will probably have the maker's mark.  Was probably terrifically expensive when purchased, so someone important had it.  Who probably depends on the type of armor.
12-14
Thick.  Quantity is traded for quality.  Much heavier than normal (may even give a Dex penalty).  Provides +1 to AC and protects from one level of armor piercing.  I always picture dwarves wearing stuff like this (and Expertly Crafted).  Think living tank.
15-16
Comfortable.  The players may not understand, but their characters will appreciate it.  If you're trying to wander around in armor all day, you want it to be tailored for optimal comfort.  Likely to be fitted for one person, and will need modifications.
17-18
Trademark armor.  Very distinctive of some individual or group.  May be made out of strange materials, might have special face mask (animal, draconic, demonic), might just have the heraldry of the original owner emblasoned directly on it.  Depending on who owned the armor, this can be very good or very bad.
19
Blessed.  Intended for the holy warriors of a faith. Will function as +1 for them, will ignore everyone else.  Probably looks very distinctive.  The classic black platemail of the antipalidan and the shining mail of their opponents are both good examples.
20
Honest to goodness magical item.  Like weapons, you should always make it interesting.
Maybe...
    The draconic facemask allows the wearer to breath flames
    Its immune to Heat and Chill Metal
    It is part of a set, and the wearer can sense the direction and state of the other wearers (of course, so can they)
    The wearer will never be hit by campatriots firing into melee (unless they're aiming at him : ) )
    The wearer's footprints look like those of a Bear
    The parts of the wearer's body covered by armor don't cast a shadow or reflect in mirrors (i.e. they might dissapear entirely or be just a floating head depending on the armor or missing a torso while wearing a breastplate)
    Gauntlets are equipped with spikes for serious hand to hand action
    The armor slays all natural insects and vermin within one foot.

    One important thing to remember about armor is that it was made to fit one person, especially plate mail.  If the ancient elven civilization made all the magical items in your campaign, its likely Burly Joe Fighter will never be able to find a suit of magical armor that fits him.  He trim companions might, but the steriotipical stocky barbarian is just out of luck.  Of course, it would be pretty mean for that to happen if you didn't sort of warn them first... *shrug*
     I always think of armor being for someone in particular, it clears up what it should do, what size it is, and a nice chunk of history in one fell swoop.  If that leather armor they found (i.e. pried off their opponents corpse) was made for a wandering minstrel it makes the likely powers a lot different then if it was for a holy assassin of Gomora (goddess of lies in the War of Shadows).
     The minstrel's armor may be plus one, repel all forms of filth (keeping it and the wearer eternally clean, might work on intellegent filth, might not), give a plus three on all dancing checks, and a sheild spell that automatically invokes when the caster is struck with a projectile.
     The holy warriors armor is plus one for infidels, plus two for the faithful, and plus three for priests; it deepens the shadows around the wearer, giving them a +10% to Hide in Shadows; and acts as an Undetectable Lie spell for as long as the wearer is lying.  When they tell the truth, their words will somehow seem hollow and unconvincing (-4 to Charisma when telling the truth, all truths detect as lies with magic).

      Anyway.  I hope I've given you some good ideas.  Low Magic campaigns are really nice because you can put a lot of love and care into your magical items.  Of course, other campaigns can use the advice just as easily its just not as easy if you want to keep track of everything.  For high magic campaigns, remember that your players will probably come up with their own theories on the matter and voice them (probably).  Sometimes these can lead to defining an item with love and care, sometimes they lead to new adventures.