One of my esteemed colleagues introduced me to this:
http://www.freerice.com be forewarned it offers the ultimate in creative procrastination. You best be cautious for this game steals time and donates rice! It's a vocabulary game that donates 10 grains of rice for each time you get a vocabluary word correct. I also feel like it's a positive application of the type of adaptive interface that the computer based GRE utilizes. As the words you're tested with adjust to your skill level.
Get out there and donate some rice!