Having fixed some bookmark issues with Nautilus (and in particular replacing the propriety bookmarks with the GTK ones), I have decided it would be cool to have a side panel that looks and behaves much like the GTK FileChooser one.
Some other file managers are also heading this way, especially Thunar
Screenshot of what I have done so far: nautilus-places.png
Of course there is still some way to go - I need to have a pathbar just below the toolbar to complete the effect. In any case this should ensure that Nautilus remains one of the best file managers available.
Submitting a patch any second now...