I'm surprised Gmail doesn't have this type of functionality. It could try to keep track of what email lists it thinks you are subscribed to, and then let you manage them all from a single page (with links to external sites if Google can't remotely manage it).

Seems like a pretty straight forward feature addition.

It's not going to solve the problem of an email list that is almost impossible to unsubscribe from, but it would still be cool to just see all the email lists that you're subscribed to in a single place.