General Issues
Check out the Intellectual Property Law Server. The forums — you can search them — are really helpful. The worldwide intellectual property link at the bottom of the page is especially useful.
The University of Texas compiled some great information on this topic.
Using Song Lyrics in Novels and Stories
Rascal E. Riter: Song Lyrics in Fiction
Brian A. Klems published an excellent article on this topic at Writer's Digest.
Writers at AbsoluteWrite had a lively discussion on the use of lyrics in manuscripts.
