Currently using SiLabs FM USB module.
Ordered from Mouser in the USA.
Reception is OK.. not brilliant.. trying to get it better.
They have a new module which does AM reception as well, but Im not sure if its out yet.
shame about the reception of this unit.. cause its very close to being excellent, but just misses a little.

Search www.mp3car.com in the hardware section for the 'Silabs USB FM' and you'll likely find my posts and others.