[StephenR]

I like to check out DayPop - http://www.daypop.com/blogrank/

The link above will show you their top ranked blogs but you can easily search for relevant blogs by going to their root URL http://www.daypop.com/ and adjusting the search parameter on the right.

Others to search are:

http://www.blogwise.com/
http://www.blogarama.com/
http://www.blogstreet.com/
http://www.blogsearchengine.com/
http://www.blogdigger.com/
http://www.bloggernity.com/
http://www.blogcatalog.com/
http://www.getblogs.com/