Most Atheros based cards are good.
Wistron Neweb CM-9 cards work fine. (minipci)
Senao 5354 MP PLUS ARIES2 4G (minipci)
Dlink DWL-AG530/AG520 (PCI)
3com 3CRDAG675 (PCI)
In general you can refer to this list: http://www.madwifi.org/wiki/Compatibility since the freebsd HAL and the MadWiFi HAL is the same. (cards reported working on madwifi-ng might not work !!)
But forget about pcmcia/cardbus cards, they might work on linux and not on freebsd and vice versa.