The TV cards by Hauppauge receive good attention for LInux use, though there is a lot of variation on how well they actually perform under LInux.
Most of the old analog NTSC cards are well supported, and can often still be purchased. The newer dual cards that have ATSC, ClearQAM & NTSC Analog like Hauppauge WINTV-HVR-1250 work fine on the digital side but aren’t supported in Linux for NTSC. For an example of current developments in this area, see this Haupage Linux page.
Extensive hardware information can be found in the LinuxTV database.
The easiest program to configure TV cards is Kaffeine. Even if you intend to use another program, Kaffeine makes it trivial to select a card, set the card’s mode, scan for channels and watch TV. If it works there you can generally figure out how to get it to work in any of the other TV programs.