I'm looking for a portable hard drive enclosure (2.5" notebook) that plugs into an SD card slot and LOOKS like an SD card to the camera. The obvious advantage being unlimited space for video recording.
But where it really comes in handy (and crucial) is when you factor in how long it takes to transfer a giant multi-GB video file from the camera's SD card to a hard drive. As far as I can tell, the fastest possible setup maxes at about 20MB/s.
(Similar to how Eye-Fi works)