If you want to search a history of your comments used under different usernames you can use a new site called Backtype. But this site does so much more. I have signed up and in the exploration stage. Join me. I also wrote a short review.
Did I hear someone out there say they do not make comments on blogs? I hope not. Because if you want more traffic to come to your sites, establish more online relationships and just let folks know what you have to say then Go Forth And Comment!