Here is the fix for USB Wifi (RT73 chip) for Lion 10.7.2. I'm using TP Link WN321G USB Wifi stick you can buy this for under 15$.
1 - Install the RT73USBWirelessDriver.kext to S/L/E using kext wizard
2 - Copy RaWLAPI.framework folder to L/F
3- Repair permissions using kext wizard
4- Reboot and open Ralink Wireless Utility (You can add this to auto starup at boot)
N.B: Remove any Ralink Utility and wireless and reboot before starting the step one
Credits, Original topic --> Link
RT73 Lion Fix.zip