The official call for paid-link reports is pretty much disliked across the boards:
Google is Now The Morality Police on the Internet
Google's Ideal Webmaster: Snitch, Rake It In And Don't Deliver
Other sites can hurt your ranking
Google's Updated Webmaster Guidelines Addresses Linking Practices
Google clarifies its stance on links
More information, and discussion of paid/exchanged links in my pamphlets:
Matt Cutts and Adam Lasnik define "paid link"
Where is the precise definition of a paid link?
Full disclosure of paid links
Revise your linkage
Link monkey business is not worth a whoop
Is buying and selling links risky? (02/2006)
Post it to