I love the LaCie Rugged drives, they're small, quiet, fairly fast, and durable. And they are bus-powered off your FireWire or USB port, so no need for a power adapter.
I would stay far away from Western Digital no matter how tempting the price is. I have a WD 1.5 TB drive I was using as a backup drive and it's horrible. Dog slow and flakey. When it's plugged in and the Mac goes to sleep, the Mac must be rebooted, actually the Mac's power cord must be removed before it'll reboot, I'm not joking. And when I had it attached to an Airport basestation, it would periodically unmount itself and foul everything up. Worst piece of technology I ever bought. And I remember the days when WD made some of he best hard drives, but those days are long gone.
I also know some people who like the "G" drives, but I haven't owned one.