Tracking Referrers

So now I’ve started tracking referrers. I’m using the referrer server variable, and running into canonicalization issues. For example, as I write this entry, there are 8 referrals from ASP.NET Weblog. But it shows up on my list as 3 separate referrers since I’m not sure how to canonicalize the URL. For example, Radio users mostly come from the Radio.Weblogs.com server, so for those users, the specific virtual folder is important. But for other sites, like aspnetweblog.com, it’s not. Anyone have a good suggestion?