It Wasn't Me! I Wasn't Even Here!

So, I was browsing Wikipedia when I saw this:

What's that? A new message for me, about my last change? I don't recall making one recently, let's take a look:

Regions of Brazil?! I made a change to the Wikipedia page on Regions of Brazil? That would not be among the topics I would consider for my specialist subject if I were to appear on Mastermind. Hang on a minute, this message is from 23 November 2008...

The penny drops. I'm not even logged into Wikipedia. I have, however, moved house recently, and changed ISP and hence IP address. Evidently I've received an IP address that was once used by a Wikipedia vandal. Let's click through and see a diff of their edit:

Nice.

I wonder what other things can I unearth on the public web about the previous users of an IP address?