Somehow, we're past 300 users on Where to Find Me! I am glad this is useful to people, but I know there's more I need to do.
I'm currently working with a few folks on a detailed policy and response to abuses of the service (most notably impersonation), and adding some technical features. The most recent features I've added are nicknames on favstars: when you fav someone, you can also add a nickname that _only you see_ to remind you who that username is.
Check it out: https://wheretofind.me/