anyone else bought a regular SD card, and chopped it down to fit? now that they're become quite cheap, it's not such an expensive proposition!
I just discovered this: http://linitx.com/viewproduct.php?prodid=11141 put an SD card into an RS-MMC slot. snag is, the SD card would stick out from your 770 by a very long way!
It also won't recognize that card, unless you perform surgery on your 770; the card door has a magnetic switch.