It'll be a little while before I add this to the projects link on the site, but yesterday I pushed a new project up to GitHub. Bootstrap Tree is a lightweight Tree component, for use with the Bootstrap framework. This is still a work in progress, and very bare bones at the moment, but basically you write some formatted HTML (nested lists with data attributes), include the css and js (very small) and it works. Currently you'll have to download the code for the example, but I welcome any feedback, suggestions, comments, etc.
I can think of several things to add to this project, but what do you look for in a tree component?