I was just in www.bunnybytes.com. They have really good info on the various litters and hays that are made just for bunnies. I thought it was great that they explained the diff. hays and in what circumstances they should be fed to bunnies.

They also gave hints on how to change a bunnies diet and not stress either the bun or yourself when you decide to go to a diff. hay. It's a worthwhile read.