My friend Joe just sent me this link: www.freerice.com. There is a fun little vocabulary game, and every time you get a right answer, they donate 10 grains of free rice to hungry people somewhere in the world.
I played today. If you get 3 right answers, you advance to the next level. One wrong answer sends you down a level. It's pretty fun. There are 50 levels, and I made it to level 34 in about 5 minutes or so. In that time I donated some 600 grains of rice to charity. That's not all that much - maybe half a cup, but like Joe said - it's better than minesweeper or hearts. During that down time between projects, we can actually do something good for the world.
Check it out.