I have used the following
Stardock Enhanced File Dialog - adds some icons and options, allows to edit the 'places' bar
Directfolders - adds some icons and buttons, allows to edit the 'places' bar. makes windows resizable (most), remembers settings and position etc.
Powerdesk dialoghelper - adds some icons, tracking of files and folders, adds a viewer
Wirekeys' files plugin - puts a very discrete bar to jump to favorites (and a few other functions) to the file dialogs, explorer, and total commander
I'm also curious about resortlabs' handy folders - mostly because i like their other 2 apps I had to look at it.
handy folders - adds a toolbar in dialogues, in normal explorer, has a taskbar icon. These are movable like normal menu bars, via the normal view menu. Offers offer a way to save/define the file extension filters which I have not seen elsewhere.
So each of them adds some features that are nice, and lacks some features that others have