Liminal Existence

This is an incomplete, but satisfying, list.

Twitter: I do architecture and code at Twitter. It's pretty great, ask me about it!
Starling: Starling is an open-source messaging system that ROCKS! (I'm biased because I wrote it, but other people have said it's awesome, so there). We use it to make the backend of Twitter go, and it's slightly easier to use (I hope!) than Solitaire. Possibly more addictive. Ahem.
Jabber::Simple: Jabber::Simple is an extraction from Twitter that simplifies the complex interactions that are required to build a relatively simple Jabber client in Ruby.
Odeo: First under the auspices of Odeo, then Obvious, I worked on Odeo building, well, we weren't quite sure, but it had something to do with podcasting.

OAuth: The OAuth project was born out of my work adding a reasonable authentication scheme to Twitter; not having a standard seemed like a gigantic waste of time, so I spent many months working with a bunch of awesome people coming up with one, instead. Now I need to actually get it working for Twitter, but in the meantime it's out in the wild, and will hopefully be making API mashups safer all over the place.
FakeWeb: FakeWeb is an Odeo extraction, and allows Ruby developers to build tests that perform HTTP requests without actually making the requests. This is essential when the requests are slow, unreliable, or impossible when performed from the testing environment. Moreover, it makes the results of HTTP requests predictible, allowing the development of reproducible test cases.