The world is welcome to the code which I created BuddyBuilder with.
I originally made it so I could blog to everybuddy.org with my IM client. 676 people have registered. A few use it regularly. I don’t actively develop it, but I could start again.
I wasn’t planning on it being an Open Source so I need to tidy up some hard coded stuff. Then it’s yours. You’ll need an XMPP/Jabber server with transports to run it, but that’s easy to do or find. I have it working with AIM, Yahoo and GoogleTalk
You can get weather by IMing mybuddybuilder, and typing weather:90210
You can subscribe to users and tags. It’s a little rough, but easily smoothed out.