You just needed to read down a little further in the list of TreeView examples. They have a very nice version of TreeView that reads in the tree info from structured html. It is just the unordered list method you were looking for. On the Yahoo TreeView main page (http://developer.yahoo.com/yui/treeview/) under ‘Quick Links’ click on ‘Examples’ and then click on second from the bottom example (Three Ways to Define a TreeView: Markup (Progressive Enhancement)). It is exactly what you want. The cool thing about it is that the heirarchy can be entirely within simple HTML and a person maintaining it does not need to interact with the Javascript at all. I took their example and quickly added some topics and subtopics at
http://staff.washington.edu/rells/test/services_treeview.html
The method (progressive enhancement) also is a big plus accessibility wise (incidently)