What are the checkboxes under the Search engine?
They are known as Google Refinement Labels

We at PoliViews.com have painstakenly labeled a growing list of political websites, blogs and editorials to help users narrow their searches to best give the results they need. By doing this we hope that users no longer need to comb through hundreds, or perhaps thousands, of often randomly-related links to find the one tidbit of information for which they're looking. We hope as well that this will give people the chance to look for opinions from the other side of the coin as well.

How do we use it?
If someone wishes to find what Conservative bloggers have said on the global warming, that person would type "global warming" into the search box then check Conservative and Blogs. This will bypass any links that are tagged as editorials, news, reference and/or Liberal. To see what Liberally-leaning sites are saying, merely change the checkbox from Conservative to Liberal.

How does it work?
We're not sure, but we suspect it has something to do with magic elves.

We hope this tool becomes as useful to you as it has to us. Good luck hunting!