I look forward to Wireless USB becoming a reality because then I can easily put some sort of large flash-based device in my car, powered from the car, and use it for backups. As my car is generally where I am I think that it would be reasonable to use such a device for backing up personal financial data and other things like that.
Sure, I’ll have to incorporate some manner of both encrypting the communication and the data on the disk, but that shouldn’t be too difficult.
It’d be interesting to try it now via Bluetooth, but it’d make the availability as a disk volume (for easy backups) a bit more complicated.