Ask HN: How do you curate your address book?

I'm participating in a Startup Weekend (#swperth on Twitter), and I pitched an idea called "Tactopus", which is a service for curating your contacts for you.

A placeholder site is up at www.tactopus.com with links to a discussion page, by the way, if you'd like to help us out with some feedback.

I figured it's basically a universal truth that we all get a bit annoyed when emails to old friends bounce, or at the thought of letting everyone know about our new phone number or email address. And I also figured that going through your address book and fixing up all your contacts is so much more painful that we just accept this all as how it has to be.

But what I'd like to know from the HN community is this: Am I in the minority here, or have I struck a chord? Does everyone already use some amazing tool that I'm somehow unaware of, or is it just not that big a deal?

So how do you make sure all your contact information is correct and complete?