Portable Bookmarks Manager Request

i think what your asking for is kinda already availiable in portableFirefox
if your looking to sync your bookmarks between your machines as well there are a couple of solutions
1. Google browser sync not compatible with Firefox 3 and its not planed to ever be
2. Foxmarks
i hope this helps
PS. there is also another extension in the works that called weave made by Mozilla but that is still very experimental