One that caught my eye is an RCA handheld which uses AA batteries instead of an imbedded battery, so you don't have to wait for the battery to recharge, just exchange cells: 3.5
RCA also has a 7" HDTV
* Disclaimer: I do not have experience with any tiny DTV sets except for HAIER and they have fair pictures and terrible audio quality.
* Additional: I looked up the 3.5" set on Amazon and read mixed reviews. Apparently it is a 'badge-engineered' set that is sold under several manufacturers names and it does not have an external antenna jack.
Here's an interesting RCA tablet/ DTV combo. Yea, it's slow, it only has a single core processor, but it's 720p, has MOBILE DTV, has an external antenna port (Mini), HDMI out, and costs only a bit more than a plain tablet or portable TV. And yea, it has a sucky battery life like most cheap tablets/tvs. But if you don't need the tablet for intensive apps and use external power (like an external power pack or 12v adapter) it may be just what you're looking for.