It seems someone worked out that the Realtek RTL2832U found in various very cheap USB DVB-T decoders can be repurposed as a complete software-defined radio. The sidebar of this subreddit seems to be the best place to start.
Update: This is the Ezcap EZTV645 from Deal Extreme:
[175189.929963] usb 1-1.1: new high-speed USB device number 7 using ehci_hcd [175190.028379] usb 1-1.1: New USB device found, idVendor=0bda, idProduct=2838 [175190.028385] usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [175190.028389] usb 1-1.1: Product: RTL2838UHIDIR [175190.028392] usb 1-1.1: Manufacturer: Realtek
Bus 001 Device 007: ID 0bda:2838 Realtek Semiconductor Corp. RTL2838 DVB-T