Best you're likely to get through USB2.0 is probably about 25-30MB/sec average. Even through Firewire you're not looking at that much better. Here are a quick couple of benches using HDTach (showing read speed only).
USB2.0
Firewire
Back on topic...I didn't ask for anything for Christmas so I just got a few bits and pieces. I've spent a bit on myself and others though, now that I have the luxury of a job I can afford to splash out a bit.
edit: If you're looking for a really quick external drive you could go for something eSATA. It uses a different connector than SATA but allows you to get basically the same speed as internal SATA.
eSATA (RAID0 with 2 750GB WD7500AAK, connected via PCI using RocketRaid 1742 card)
http://xs222.xs.to/xs222/07503/RAID0.PNG