That looks pretty complete, but I'll tell you how I come across them...
I start off just at Radio Shack and get a list of some of the confirmed frequencies, then I consulted the Radio Reference Database for additionals listed under DNRC, and then I just called up the Forest Service and asked them.
What region are you specifically needing? I have some other listings for Bozeman/Livingston/Ennis around somewhere, but I'd have to look.