No, i have not really seen many different types of adapter but that mobiadapter is the sort of thing i expected there to be an abundance of.
I mean there must be something like that out there but instead of an normal usb2 port it has a mini usb2 port so you could just plug in an external hdd right? lol
If not i claim the patent right now:-)
It just seems like that would be a really obvious easy thing for longer recording times etc. i have a 1 tb drive that would easily fit next to my gh2. im not sure about transfer rates etc but isnt this a decent viable idea?