I've run across quite a few really great resources for tips on freelancing and communicating correctly with clients, so I figured it would be a good time to start a collection that I (and whomever else wishes) can add to. Feel free to post your own in the comments!
[Tips for Effective Communication with Your Clients]
[Freelancing 101 for Graphic Designers]
[AIGA Salary Survey 2009]
[Standards for Professional Practice]