BuddyPress.org

Yah… always best to use unordered lists for navigation. It just makes the most sense semantically speaking. Once you have your navigation being output as nested lists… there are any number of CSS/JS solutions to hide the nested lists and turn them into drop downs. The most lightweight solution is the old tried and true suckerfish menu… which is pure CSS with just a teeny tiny bit of javascript code to make it work in IE. But since jQuery is already included in WordPress… may as well go with something a little more fancy… with a mouseout delay… etc.