Check out my blog. My teachers will be posting their favorite apps later this week. I have a rubric that I have developed for rating apps that is now being used across the globe. It is linked on my blog as well. I think you will find it helpful.
Wow. Seems like so long ago when I last posted this. Things have moved on a lot for me since then, and I have no amassed a collection of apps that I find useful for my 4th grade class. You can see this list here if you are interested...
It's not quite as updated as it should be as I also have all the Everyday Math Apps that were free recently, and a couple of others too, but it will give you an idea of what I like.
For anyone else who has not heard, there are also 24 free Kindergarten.com flashcard apps available until the end of April.