I want to say imenu, but again this was over a year ago and I don't see anything conclusive in my vestigial .xemacs files. Likewise I vaguely recall having to do a little work to get things going, but on the order of an hour or two not days. As for how well it worked, for the most part it found subs and packages pretty well (again, foggy memory here). It worked well enough I had a permanent keybinding set aside for it, at least. :)