Can anyone recommend a good PCI 802.11b card for use with NetBSD 1.6?
Just as a client, not as an access point.

Should I be running NetBSD-current instead, to get support of more
cards?

I picked up a Netgear MA311, and the kernel recognizes it:

wi0 at pic1 dev 4 function 0: Intersil Prism2.5 Wireless Lan
wi0: interrupting at irq 11
wi0: 802.11 address 00:09:5b:11:b3:e3
wi0: using RF:PRISM2.5 MAC:ISL3874A(Mini-PCI)
wi0: Intersil Firmware: Primary (1.0.7), Station (1.3.6)

Unfortunately, when I try to actually send data on it, the
driver spews errors:

wi0: wi_cmd: BUSY did not clear, cmd=0x11
wi0: timeout in wi_seek to 13c/0; last status abfc
wi0: timeout in wi_seek to 13c/44; last status abfc
wi0: wi_cmd: BUSY did not clear, cmd=0x10b
wi0: xmit failed
wi0: device timeout
wi0: wi_cmd: BUSY did not clear, cmd=0x2
wi0: wi_cmd: BUSY did not clear, cmd=0x0
wi0: init failed