http://www.miniclip.com/games/bloxorz/de/

Cubical puzzler, simple but fun until you reach your frustration limit :P

Gluey

http://www.kongregate.com/games/KingDotCom/gluey

Gluey is a small, physics-based puzzler built in flash. It revolves around differently colored blobs that the player has to "pop" to gain points. It's pretty simple but it's smooth graphics and feedback just pull you into the flow. Especially the Zen Mode is great for killing time.