I'm pretty paranoid about making sure that backups are done on all of my Macs. That's why I carry a small Western Digital MyPassport hard drive with me wherever I go with my MacBook Air, since I do at least one Time Machine backup a day -- even when I'm on the road.
This is my second MyPassport drive. That's not saying that anything is wrong with the Western Digital drives; it's just that the first one I owned fell off of a classroom desk while a backup was in progress, pulling out the USB cable and dropping about three feet onto a hard floor. The drive appeared to be OK, but never worked again.
That's why I was happy to hear that OWC announced the Mercury On-The-Go Pro series of portable bus-powered SSD drives yesterday. Solid-state drives, since they have no moving parts, can put up with a lot more abuse than traditional platter-based drives. They also offer better read performance than regular hard drives, and are often less power-hungry.
The drives come in three different capacities -- 64 GB (US$279.99), 128 GB (US$449.99), and 256 GB (US$729.99) -- and all offer 64 MB of cache, as well as Firewire 400/800 and USB 2.0 interfaces. Being bus-powered, they don't need an AC adapter, making the On-The-Go Pro series perfect for road trips.
While SSD drives are still more expensive than traditional hard drives, they're definitely more rugged, and in the long run that might be less costly than replacing a dropped hard drive. I've had extremely good success with OWC's products in the past, making this a doubly-attractive proposition. Of course, making sure my students don't cause my drives to take a dive off of a desk is a cheaper solution!