I needed yet another external drive so I can test the Leopard beta and not wipe out either my internal drive or the backup drive I brought with me to SF, so I decided to pick one up at CompUSA.
After looking at several models, I picked the 120 GB Seagate FreeAgent Go. When I got it back to my room, I discovered it included a USB Y-cable, with two connectors on the computer side. There’s a reason it came with that cable: it draws too much power for a single USB port, so you need to connect it to *both* ports with one of the connectors providing power only. If I connect it to a single port, it won’t work.
I ended up returning it and getting a Western Digital Passport 120 instead. This one works nicely from a single USB port.