No Apple experience, but....
For PC Laptop I have used this:
Hauppauge 1191 WinTV-HVR-950Q TV Tuner Stick/Personal Video Recorder with Clear QAM and Remote Control (Black) The price bounces between $48 and $60 on Amazon. But I have found that it really needs a powered antenna to pick up over the air signals now that everything is digital.
For Android I haven't tried a USB tuner yet.
This looks interesting and I may have to have one when it comes out.
http://www.techhive.com/article/2023760 ... uners.html
http://www.rca.com/press-release/watch- ... tv-tablet/
For the van, now I just carry a 7" portable TV with a cable connect if the campground I am in has cable. It has a little antenna with it, but again works best with a powered one which I don't bother to carry. Watch videos on my Asus tablet (Android).