Not everyone has considered guest blogging, but it can be a very worthwhile way to reach new audiences. Basically, when you write a guest post for another blog, that blogger gets your content, a fresh perspective or some aspect that he/she does not feel qualified to cover. In return, you get exposure to that blogger's audience, some of whom will follow your link and check out your own blog. And you have two bloggers promoting your material.
Here are two recent examples of guest posts I wrote on other blogs:
http://thesocialrobot.com/2010/05/ho...earch-engines/ http://www.canuckseo.com/index.php/2...not-to-dot-ca/
I have two others waiting for publication and I just submitted one for a client. This is a trend I expect to see a lot more of (although I personally will never be able to keep up this pace!)