The Onion - Internal link: http://www.theonion.com/content/index - main page at http://www.theonion.com/.. As I recall from a year or so ago (ie from about 2000), new issues go up on Tuesdays.
Parental Note: this site is often R-rated.
Another good satirical site: "Something Awful": http://www.somethingawful.com (Oct 16, 2005) Parental Advisory warning (as usual) -Use their search feature to search on Geocities, find their Geocities review pages and look at other awful Geocities sites like mine...

Here's the obligatory Dilbert:
http://www.unitedmedia.com/comics/dilbert/archive/

Electrical Engineering humor -- because you can't spell "Geek" without EE!: http://www.repairfaq.org/ELE/F_Humor.html
The Grad Student Emotion Checklist: http://philip.greenspun.com/humor/graduate-student-emotion-check-list (July 12, 2005)
The Geek Code: http://www.geekcode.com (July 12, 2005)

Other comics
Peanuts http://www.unitedmedia.com/comics/peanuts/archive/
For Better or for Worse http://www.fborfw.com/strip_fix/archives_calendar.php (Oct 2, 2005 just after I found out about its new location!)
Spider-Man http://www.kingfeatures.com/features/comics/spidermn/about.htm (went pay as of July 25, 2005)
Brenda Starr http://www.comicspage.com/brendastarr/brendastarr.html (link moved to this as of June 13 2004 - still free!)

For the easily amused: The Canada Dance Page: http://www.homestead.com/100percentcanadian_eh/Canuck.html (set your PC's midi volume to half while beginning to play this).

PhD Comics -- life as a grad student! "Piled Higher and Deeper". Archives ("List all comics"): http://www.phdcomics.com/comics/archive_list.php. Home: http://www.phdcomics.com. Latest comic (the user interface for this site is good, but not great): http://www.phdcomics.com/comics/comics.php (As of Jan 2006 updates are not showing up on the archive pages, so check this (foregoing) link first);  Here's an introductory selection: http://www.phdcomics.com/comics/aboutcomics.html -- notable and funny are the "Grad Studeent Documentary" and "Newton's Three Laws of Graduation" (both are sequences, so click "Next" and read!). (Aug 30, 2005)

March 7, 2004 More weird comics, updated a lot more often than "Argon Zark": http://www.keenspot.com/; found at this site are some of the following:

College Roomies From Hell http://www.crfh.net/ (semi-SF or Fantasy; somewhere between PG-14 and R-rated) -- I've read through this series as of Aug 2004; there are a lot of strips by now. The story grows on you. These two were cute: http://www.crfh.net/d/20000919.html, http://www.crfh.net/d/20000921.html. Guide for new readers: http://www.crfh.net/new.htm; Storyline index and description on same page (Spoilers!): http://www.crfh.net/new.htm#storyline_guide.

Schlock Mercenary http://www.schlockmercenary.com/ (SF military humor; appears to be PG-rated). First cartoon in series at http://www.schlockmercenary.com/d/20000612.html

Sluggy Freelance http://www.sluggy.com/ (appears so far to be SF; seems to be PG-rated)

User Friendly http://www.userfriendly.org/ (Geeky computer humor - pretty much G-rated. I think it's in some newspapers). I've read the whole series as of Aug 20, 2005, and I can generally recommend it to tech/business readers. It's really cute -- (especially the little "Dust Puppy" guy who was born from dust inside the servers) and not as bitter as "Dilbert". The author is Canadian, so there's some (very infrequent) Canadian content. He does some pretty good rewording of old pop songs on Sundays and an archive of links to those is specially available on the site. Here's a sample of a strip: "One Night in Our NOC": http://ars.userfriendly.org/cartoons/?id=20031019&mode=classic. However, there is a strong left-wing (anti-property-rights) viewpoint. The RIAA and those who want to protect their content are not totally in the wrong, and a lot of this heavy file-sharing is morally questionable. Even the aboriginal North Americans ("Amerinds", to advocate a term) had intellectual property rights to their entertainment content (stories and songs). Not all tech types are left-wingers; in fact, the libertarian viewpoint is heavily represented. This is a demographic which the author of this strip should not ignore. (updated Jan 28, 2006).

Strip of Nov 19, 2000: Certificate of emigration from the US to Canada due to the 2000 election: http://ars.userfriendly.org/cartoons/?id=20001119. (updated Jan 29, 2006)

Queen of Wands http://www.queenofwands.net/ - a soap-opera/relationship strip. R-ratted for swearing and sexual talk; little to no nudity. Some exaggerated off-panel cartoon violence. I've read through the entire series as of Aug 1, 2005. First comic http://www.queenofwands.net/d/20020722.html; last comic http://www.queenofwands.net/d/20050223.html. Since then it has been in reruns, with commentary added. Here's a side-strip which works off frustration due to a common pet peeve often felt by those who can spell: http://www.queenofwands.net/d/20031003.html.

Something Positive - http://www.somethingpositive.net/ - another soap-opera/relationship strip (I'm into these). I was hooked into reading this due to a crossover from "Queen of Wands" (which began at (rerun strip): http://www.queenofwands.net/d/20051124.html, or http://www.somethingpositive.net/sp05112004.shtml). Sun Dec 18, 2005. This strip features (sometimes) a rather surreal pink cat that can take any shape (some, rather, most, of the shapes it takes look like they can cause nightmares). It's also rated R for language, sex and violence. There is also truly mature content. The main character from "Queen of Wands", Kestrel, has been adopted by this strip. I liked the art more at the beginning of the strip, which is not normal, since webcomic graphic artists usually improve drastically due to the practice. Reading about supportive friends and family is always balm for my soul, even though these characters act quite "whacked" much of the time.

Here are some sample strips that I enjoyed (or were noteable): (updated Jan 28, 2006)

A very satisfying part (warning: off-colour): http://www.somethingpositive.net/sp12312005.shtml

Choo-Choo Bear woken by his cell phone: http://www.somethingpositive.net/sp12302005.shtml

Kestrel gets hit by a car - http://www.somethingpositive.net/sp02242005.shtml (fortunately she turns out OK)

Really cute picture of the cat ("Choo-Choo Bear") -- looking more catlike and less surreal - http://www.somethingpositive.net/sp12212004.shtml (I refer mainly to the second picture -- this is also some foreshadowing about the person trying to pet the cat)

Gay Marriage in Canada - http://www.somethingpositive.net/sp05162004.shtml

End of the QoW cross-over: - http://www.somethingpositive.net/sp05142004.shtml

Spay Your Catgirl - http://www.somethingpositive.net/sp01192004.shtml

STICK! STICK! STICK! STICK! - http://www.somethingpositive.net/sp01072002.shtml - this one made me laugh until it hurt. Pain can do that.

SuperMegaTopia http://www.supermegatopia.com/ (Disney-style-"Funny animal" superhero/SF; so far appears to be PG-rated, for bulging bosoms)