Lightning Dodger:

In the Thunder Plains, your objective is to dodge the lightning.  To dodge the lightning, you press the X button when the screen flashes.  Once you have dodge a certain amount of lightning you are rewarded with items.  They will be in the treasure chest outside the Travel Agency.

Rewards
Dodge Lightning	Receive
5 times	2 X-Potions
10 times	2 Mega-Potions
20 times	2 MP Spheres
50 times	3 Strength Spheres
100 times	3 HP Shpheres
150 times	4 Megalixirs
200 times	Vensus Sigil (required to unlock Lulu's legendary weapon)

Getting hit by the lightning also takes HP from your characters, but if you survive a number of bolts, you can also receive prizes.

Rewards
#of times struck by lightning	Receive
30 times	Ether
80 times	Elixir

Butterfly Catcher:

When you enter the Macalania Woods, you will meet a creature who explains the Butterfly Catcher mini-game.  To begin the game, move toward the closest butterfly.  You have to chase down seven blue butterflies before time runs out.  Avoid the red butterflies becuase they'll call powerful fiends and remove 1 second from the remaining time.  If you catach all seven blue butterflies before time runs out, a new treasure chest apperas.  The chest will disappear if you leave the area, so don't forget to open it and claim your prize. 

There are two places where you can play the Butterfly Catcher mini-game.  One area is in the Macalania Woods-Central, near the creature who explains the game, and the other area is in Macalania Woods-North.

This mini-game gets more difficult as the story progresses, but the prizes keep getting better.  The timer is first set to 40 seconds, but after you have defeated Spherimorph, the timer is set to 30 seconds.  Once you gain control of the airship, the number of red butterflies increases greatly.  If you return to the Macalania Woods in the airship and succeed in both areas, you will be able to obtain the Saturn Sigil, which is needed to activate Kimahri's lengendary weapon, the Spirit Lance.

Village of the Cactuars:

After you have gain control of the airship, return to the Sanubia Desert.  There will be a large rock, and on it, will be a picture of a Cactuar.  Each time you examine the rock, you would be given a clue to find one of the 10 hidden Cactuars in the desert.  After finding each one, you will have to play a game of "Red light, Green light."  If you touch the Cactuar before time runs out, you will have to fight it.  No matter if you win or lose the battle, you will receive a sphere bearing the name of the Cactuar.  Go back to the rock, and insert the sphere into the rock, and it will then give you a new clue telling you where the next Cactuar is.

Cactuar Locations
Oasis	Near the frist Save Point
Sanubia Desert-East	In an alcove to the east, north of the tent with the Save Sphere.
Sanubia Desert-West	Serach the sign near the Cactuar rock that says 20% off.
Sanubia Desert-Central	Near the ruins to the west.  Look for two Cactuars running around the desert.
Sanubia Desert-East	Near the Save Point under the tent.
Sanubia Desert-Central	Trapped in a treasure chest in the far west.
Sanubia Desert-West	Inside on of the sand whirlpools. You must exit and re-enter the area.
Oasis	Releport back to the airship and go on to the outside deck.
Sanubia Desert	Return to the Cactuar statue and the last one automatically apperas behind you.

After putting in 9 shperes of either type into the rock, the sandstorm protecting the Cactuar Village will stop. You then search inside for lots of Cactuar encounters and two special treasure chests.  One will contain the Mercury Sigil (needed to activate Rikku's lengendary weapon), and what the other chest contains depends on how well you did.

# of Spheres	Receive
Up to 2 named spheres	Potion
3-5 named spheres	Elixir
6 or 7 named spheres	Megalixir
8 or 9 named spheres	Friend Sphere