In Camino, if you get info on a bookmarks folder (Command-I or Control-click and select Get Info) and check the box for "Use in Dock Menu," all the links in that folder will appear in the pop-up menu for Camino!
[robg adds: Normally I wouldn't run a hint based on selecting an item in a dialog box, but this is a good update to a previous hint that had a much harder workaround for earlier versions of Camino (Chimera).]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030422143657367