One of the mysteries that I don't think a lot of people understand is that search engines seem to love blog comments, so much so that leaving blog comments can actually help your SEO efforts.
The reason that search engines love blog comments is that well, as I once described them, search engines are spider demons who are pretending to be human beings, who are experts in whatever terms and subjects that you punched into the query form.
And the way that the search engines do this is by weighing factors, such as the number of links there are to your webpage, and where it is coming from.
Think of each comment you leave (where you are allowed to place your website into the information field or leave one of your profile addresses) as a thread in a spider web. And if lots of people like the site that you commented on, the thread is thicker and heavier. You also have a heavier thread if your site and the site you are commenting on are actually about the same subject matter.
Basically, the little spider demons that are search engines count the number of times that the search term is found on your page (decide if it is a balanced number), and then factor in the weight of all the threads to your page to determine exactly where they are going to place your page in the search results.
So how do you use this demonic thought process to your advantage?
Be selective about what blogs that you comment on (unless you are doing a networking exercise like the commenting part of the UBC). Make sure that your site is related in the type of subject matter.
Try to write meaningful comments. If you can engage a blogger in a conversation, the little spiders notice and add more weight to their opinion of your threads.
Don't be afraid of linking to posts done by your favorite bloggers. In fact, linking to a post that you have commented on creates a double thread for the spiders to weigh.
The mysteries of SEO is simple once you start treating search engines as the demonic comment loving spiders that they really are.