If you're one of those considering a blog, check out this great article I found by Aaron Uhrmacher: http://bit.ly/UMJLm.
Plus, here are a some blogging tips I've learned (the hard way):
1. Develop a blog “persona” and stick to it!
2. Make certain your content is valuable and interesting.
3. Demonstrate expertise. Become a content expert.
4. Add links--don't make your reader "look it up."
5. Watch the self-promotion--it's a turn off.
As I learn, I will gladly share.