Seagate has been working on some itty bitty 7 millimeter HDs that are among the thinnest consumer magnetic platter drives in the known universe, and they've stuffed them into some slick new cases including a portable USB-powered dual-drive RAID system.
Seagate's new ultra-portable GoFlex drive comes in a metal case that's only 9 millimeters thick, which Seagate says is a full 38% thinner than their previous generation. This is made possible by some 7 millimeter thick 2.5" drives that still manage to deliver 7200 rpm performance via USB power, and you get a solid 340 gigs for $99.
If you're a Mac user (or even if you're not), Seagate is also coming out with a limited edition drive that manages to stuff a full terrabyte into that same tiny form factor. It's 'limited edition' simply because the technique for manufacturing drives with a density that high is kinda new, and Seagate hasn't been able to ramp it up yet. The 1TB drive will be about $200.
Seagate also showed off a concept they're calling the 'Data Lunch Box.' It's a portable RAID system containing two of those tiny 7mm HDs, also powered completely via USB. You can have it do full mirroring for redundancy, but if you set it to stripe across both disks, the performance is actually better than an SSD drive at about 1/10th the cost per byte.
All of these drives have Seagate's GoFlex system, which lets you snap different connectors onto the drive cases to give them whatever interface you want, including USB 2.0, USB 3.0, Firewire, and eSata, and Seagate is currently trying to have GoFlex adopted as an industry standard so that third party manufacturers can take advantage of it too.