zd1211 (Score 2)

There are quite a lot of USB 802.11b/g dongles out there containing the zydas zd1211 chipset, which has a reasonably active GPL development effort based at http://zd1211.ath.cx/, including ongoing work from the manufacturers, and aiming eventually for inclusion in the main kernel tree. My company has had a lot of success using devices with this chipset under linux.