urlsplit allows you to map multiple URLs into a single.
I created http://www.urlsplit.com/KXOpyy8v for 3 of my OpenIDs. Each time you try the URL you'll get one of the 3 OpenIDs (or a mystery link).
I think this service could be really useful for someone suffering from multiple personalities. Provide the split URL to an OpenID RP and sit back and wait to see which persona you get.