I've been looking at this Netgear, the Ericsson W25 and the Proxicast for use at work. The Netgear and the Ericsson have their own 3G modems but the Proxycast takes a PC-Card.

The most important requirement for me is upload speed, so being able to choose the best 3G card I can get hold of (plus the ability to swap to a better performing one later on) is a big plus, so I'm probably going to spring for the Proxycast one. However the other two look great if upload speeds aren't as important.

EDIT: Looks like the Ericsson has been superseded by the W35.