Geohashing IRC channel
At those moments that you want to talk about geohashing but everyone you know is either asleep or feigning death, turn to the #geohashing IRC channel on Foonetic (irc.foonetic.net). (No IRC client? You can use the Mibbit web-based client or qwebirc.net's web-based client) IRC is one of the oldest real-time internet communication modes, so it's simply a text-based chat room. Nota Bene: It can take up to 15 minutes for someone to notice you've said "hi", so be sure to leave your chat window open even if no one responds right away!
A modern web browser should Do The Right Thing when you click on the above link, opening a new window in the channel. If that doesn't work for you, you may have to download an IRC client for your web browser, and if you're using a sufficiently duct-taped system that you need to do this, then you probably already know how.
There isn't much. You can see who is in the channel (by the named green dots in the right-hand column, on Firefox). Sometimes people suffix their screen names with "afk" or "lunch" or the like if they aren't actually there, but not everyone does. Type in the text box and hit return to send a message. #geohashing custom doesn't include the whole channel chorusing "hi" and "bye" for people connecting and disconnecting and the only demographic information you'll be quizzed about is your graticule.