This 30 day teacher tech challenge is a pretty good list of free and useful educational apps for teachers and their students.
http://teacherchallenge.edublogs.org
So far I am already using #1 – Wallwisher, #3 – Bitstrips for Schools, #7 – Kerpoof, #11 – Skype, #12 – Animoto,
#13 – VoiceThreads (although not free for students), #17 – DropBox, #18 – Jing, #19 – Audacity and #22 Little Bird Tales,
Want to investigate: #4 – Classtools.net, #5 – Edmodo, #6 – DoInk, #15 – Livebinders
ict4kids.ca 