I posted about this site once last year, but I thought it would be a good idea to share it again.
Free Technology for Teachers by Richard Byrne
Mr. Byrne is an educator/blogger/ and speaker. He was the "keynote" speaker at last year's TIE conference in Rapid City.
I would highly recommend following his blog, or if you are a twitter user...you can follow him on twitter, as he is constantly posting his links to his articles on free technology resources.
To be honest, I'm not actually sure how he gets it all done, as he is a teacher, and all his blog updates, and his speaking engagements.
It's a really excellent resource, complete with discussion of many, many different web applications, iPad apps, free guides and favorite resources.