I have found so many great websites that provide high quality learning games for my students! I have to post them so I know where to find them... and how to share them!
GUDLI So many great games for all curricular areas, I don't even know where to begin!
ABCya.com Great learning games arranged by grade level.
Funbrain Playground Offers math, reading and just plain fun games! You can also read issues of Diary of a Wimpy Kid
Topmarks says it is "The best, free interactive interactive whiteboard sites" and it is true! Math, literacy, science, history, geography, art, music and even religious studies!
Scholastic's Interactive Whiteboard Resources: Not very well organized, but if you have time to look around, there is some great stuff here.
Smartboard Wiki: These lessons were uploaded by Library Director Christy Heins. Not just library lesson!