Ah, I didn't look hard enough -- apparently the section is now called "Top Contributors". (I wasn't looking at "my page," because I don't have a page.)

There's a chicken-and-egg problem here, though: I would never be able to find my username this way, because I have not created or joined any wikis under this identity. So the solution for someone in my situation would seem to be to start signing in, and click the "forgot my password" link to request a reminder by email.

Jeremy, does this scan?

 out of  found this valuable. Do you find this valuable?