BlogHerald explores the ettiquette of membership in the blogosphere.

“Treat others as you would like to be treated in terms of referencing and links, we all love links and sure, I tend to be generous with them, but I’m generous with links because I want to be linked back, and its certainly doing ok for me so far. Be stingy with links and you’ll find that you won’t get as many links in return. ”

A commenter draws a useful distinction between references and links.... References suggesting a certain quality in the original material.... Either way: Be generous with your attributions and you shall be rewarded...

See also Duncan's expanded guide to blog referencing.