There's also this site:
maccaspan.com/forum
You have to register, but it's quick and easy. This site has stuff from the Beatles, as well as solo material from John, Paul, George, and Ringo, and, occasionally, from non-Beatles artists.
And, you might try:
octaner.blogspot.com
Another great source for Beatles-related stuff. No registration required.
Forum:
Buy/Sell/Trade