Yes, the title of this blog says what it says. You can track your comments with Backtype. When you sign up, you enter your information with websites you use when filling out forms and social services you use that you comment (like Twitter, MySpace, FaceBook, MyBlogLog, and more.) Once you have set this up, the site will post the comments you have made at sites using the URLs that you included.
Truthfully I think they should just list a bunch of services and you just put your ID number or your username, and it would be better, but overall, I think it is a handy service. You can always fall back on it to see what you have done recently, or for bloggers, it could be great reference for quoting. The site also serves as a bit of a social media type site where it also recognizes others online who are members of the service that you have talked to before. It is also a great reference in case you made a comment before turning in for the night, wanting to visit, and forgot to either subscribe to a site’s RSS feed or even bookmark it.
As an example, you an view my Backtype profile to see the comments and what it is about.