I have three.
- An obscure dongle device from Evga, Evga inDtube Tuner, can be difficult to get going in linux, due to an apparent funky IF center frequency but I've put some good notes in the linux TV wiki to help getting it going.
It's not actively marketed anymore that I know of but ya can find em pretty cheap online, like ebay, etc. Performs pretty well on my outdoor antenna system.
- Hauppauge Aero-M, another USB dongle device with ATSC M/H support. Performs just as well on my outdoor antenna system. Think I got mine for ~ $60.
- ATI 650 USB Combo, which doesn't have any linux support at all.
I would suggest going thru the linuxtv wiki of ATSC devices supported in linux.
http://www.linuxtv.org/wiki/index.php/Hardware_Device_Information