Most of the designers who read my blog more than likely have a blog of their own in some form or another, so I know that there is no need to preach to the converted. For those of you or may be thinking 'should I or shouldn't I?' I've a link for you!
Head over to www.mostinspired.com and have a quick read of the reasons why you should.
Personally I like the bit right at the bottom that tells you to 'blog to reduce your stress levels'. Though do keep in mind that depending on your blog you might not want to vent everything that ticks you off.