Build your towers out of different elements, allows you to completely customize those towers, just like it's little brother: WhenHellFreezesOver. This game is better balanced and has a very nice map.

BitmapTD is a pretty basic looking towerdefence game with sprites with some classic game monsters as bad guys. This game seems to be based on Element TD 2 with a camera that can follow the creeps.

Defend your girlfriend against lines of creeps, game from Addicting Games. Looks really good. Towers with a nice range too.

Prevent aquatic life from entering your water station by building towers. Click on fishes to attack them. As you progress through the levels, more towers will be unlocked. (sorry for the lousy image)

Very basic TD game, no upgrades, no path. Just build towers and choose them right to keep the enemies away.

A science-fiction defense game from Packed. Build large turrets to shoot down the enemies in this beautiful game.