Lately I've been having a lot of trouble with getting a large amount of spam on my blog via trackbacks and deleting them manually is really one big job. Finally I got my solution to the problem of trackback spam HttpModule based Generic Trackback Spam Blocker for ASP.NET.
HttpModule based Generic Trackback Spam Blocker for ASP.NET can be plugged into any ASP.NET web application, for example, into ASP.NET blogging engines such as .Text and dasBlog, and that you do not need to make any changes to the application itself. The solution itself is simple and uncomplicated and you can download the HttpModule and it's source too.
Check it out..