List of wifi cards compatible with aircrack :
Here you can find a list of wifi card who have been tested with succes for aircrack.
Most are wifi card with atheros and ralink chipset.
The Boss' selection:
The best card, I've buy and tested them for you ;)
Wifi usb cards :
D-Link DWL-G122 ralink chipset
linux
Linksys WUSB54G Only v4
chipset ralink
linux
Wifi Pcmcia cards
MSI CB54G2 Chipset ralink
Linux
D-link g650 Atheros chipset
Linux + Windows
Netgear WG511T Atheros chipset
Linux + Windows
Proxim 8470-WD Atheros chipset
Linux + Windows
PCI cards
MSI PC54G2 Chipset ralink
Linux
Netgear WG311T Chipset atheros
Linux + Windows (inject paquet under windows too)