Smart Apps for Kids is a great tool for finding free Apps and getting reviews. They will notify you if an App is free for a certain time period.
Check them out here!
I really like using the IPad for intervention. Montessori Crosswords is an App with a movable alphabet that can strengthen phonics skills for students in grade K-2.
Marble Math is a great App for practicing math skills that can be aligned to Common Core Standards.
What Apps do you like?