"Whether you buy a whole drive or build one, a wealth of different options exist for storing your digital life. Depending on your needs, you can go with large format, large capacity drives, tiny pocket-sized drives, and even battery-powered or bus-powered hardware. The ability to roll your own also exists. We're looking forward to eSATA becoming more mature. We'd love to see a multifunction case, like the CoolMax CD-311, that offers FireWire 800, USB 2.0, and eSATA support. Better yet, if you can use a 2.5-inch hard drive, you can probably build a viable RAID system out of a stack of pocket-sized drives. RAID on-the-go? Now that should be interesting."ExtremeTech has an review of external hard drives, in various forms, greater than 6GB. I was quite impressed with the scope of the article and if you want to learn more about all the different type you'll want to check it out also.