I have been doing a lot of blogging lately. Not necessarily because I think that sharing random thoughts is productive, but because there are few better linkbuilding tactics. I am maintaining three blogs right now... this and two others. One of my others was created in support of our forthcoming product rollout. I'll tell you more about them later.
Sure, you can add comments to other peoples' blogs. You can buy links. You can get other people to write about your company and/or product. But if you really want some linkbuilding magic, write.
Typepad has done wonders for us -- I get a lot of blog traffic from people searching for random things. It is probably a function of the fact that Typepad has an insanely high reputation with Google. I help things by writing 2-3 times per week. My 114 posts to date over the last 11 months create 114 pages with links to my company, my LinkedIn profile, etc.
I haven't been quite as fortunate with Wordpress yet -- my hunch is that Wordpress doesn't quite have the same reptuation with Google. I'll know more with more posts. All I know is that I don't spend a lot of time writing, but it's working as a cheap linkbuilding tactic. And I kinda like it.