1. The Council Wars series by John Ringo starting with There Will Be Dragons has a few.
http://www.amazon.com/There-Will-Dra...2144993&sr=1-1
2. Almost any book by Jack Chalker has a TF or TG in it. Go with Well World to start.
http://www.amazon.com/Midnight-Well-...2145028&sr=1-1
3. Interesting Young Adult series it has lots of Panther TF's in it.
http://www.amazon.com/Dream-Year-Cat...2145072&sr=1-1
Of course there's always
http://metamorphose.org/ which lists a few zillion more :P. Although I can speak from my own experience that those three series I listed are awesome.