The world's largest font
This site lets you spell using Google Earth and buildings that resemble letters. My favorite is
http://www.geogreeting.com/view.html?zdgZ-zE_+rs!
http://www.geogreeting.com/
Base Jumping Game
Hit the space bar once to jump and then again to deploy your parachute. Be the first to land... but not too hard!
http://www.vivalagames.com/play/basejumping/
Walking on water?
Just add corn starch to water and you get a substance that exhibits both liquid and solid properties. When gentle forces are applied, it behaves like a liquid. When greater forces are applied, it acts like a solid.
Watch the video of a few guys from Spain walking on water. Then read the Wikipedia article to learn more.
http://www.makezine.com/blog/http://en.wikipedia.org/wiki/Non_Newtonian_fluid
3D game in Flash
Just use your mouse to steer. Yes, you will tilt your head and body while playing this!
http://www.albinoblacksheep.com/games/missilegame3d
Flavored ammo?
Shoot and season at the same time!
http://www.seasonshot.com/How.cfm