LaCie Little Big Disk Thunderbolt 2 External Hard Drive
As far as LaCie knows, this is the "world's fastest portable hard drive." It boasts speeds of up to 1,375MB/s, which is the kind of speed you want for 4K video editing. But it can also come in pretty handy for backing up lots of photo files. According to the Lacie rep on the floor, it can back up 300 GB of data in about four minutes. That's pretty fast.
It actually has two solid state drives inside and connects via a Thunderbolt port, which can be daisy chained to add more drives or displays. It still needs to be plugged in to an outlet (it takes too much juice to be BUS powered), but it has an extremely small form-factor thanks to the SSDs inside.