If you're interested in backing tracks, there's a great resource over on the BHO. Mark from the UK has a thread full of backing tracks, about 50 or more by now. He adds songs almost daily. All of his backing tracks are for free download, so no one is without a jam session this winter. Almost all of his songs are in recorded in 3 different speeds, tailored to fit your level. All you have to do is right click and download. They are all done in Bluegrass style.
Mark's thread is a GREAT resource, and it's free. Combine Mark's thread with the Flatpicker Apprentice website, and you probably have all of the backing tracks you could ever need, except for very rare, obscure tunes. And you spent no money. Let me know if you have a problem downloading from Mark's thread.
These resources are AWESOME for banjo players, and GREAT for mando players and flatpickers. For fiddler's they are also great, but there are probably not as many of the obscure fiddle tunes available. But it's free to look around and download just what you want or need.