uxn is a minimal stack machine architecture developed by Devine Lu Linvega. It's used, along with a set of emulated I/O devices to create the varvara platform (previously also called uxn). This page is an index of things I've made with and for varvara, and useful links.
Resourcesuxn assembly reference
varvara page - has some documentation of the devices
sejo's uxn tutorial - supercedes what used to be here.
uxn on lines
the channel #uxn on esper.net IRC is another community hub for uxn developers and users.
I've made some things for uxn myself:uxn I/O for the monome grid
more on the grid