[jlehman]

Canvas is pretty cool: https://github.com/yosoyubik/canvas

There's a bittorrent tracker you can read about on the mailing list too which is pretty neat.

There are a couple of folks working on supporting ship-to-ship bitcoin payments, which is very nearly to a working demo.

If you haven't been on in a while, Landscape (the web client that ships with Urbit) itself is also really awesome.