There are over 100,000 iPad Apps alone out there. It is impossible to review all of them or to make recommendations about the best free ones. One day an App could be free and the next it could be full price. I've gotten one App that was free only to find out the next day that it cost $37.99. There are many ways to find out about free Apps.
Check out the Forum to find out how to get more Free Apps. Then come back here for some more great links that will amaze you.
The first link you should know about has been an amazing tool for the district to have discussions among it's employees from all over the Twin Cities area. It is the Innovation Forum Mobile Learning section.
One of my favorite Blogs is one that is kept up by a Speech Pathologist who has found many great Apps and has broken it down by category and has a link directly to the App Store if you click on it. Check out Cindy Meester's Blog.
Finally, you have had a chance to explore many different Apps through a number of different sights. Add to this forum some thoughts on Apps.