Many moons ago I dabbled with MythTV to record over the air TV. It's an open source home entertainment application. Then DTV came along and the tuner card hardware I had was going to need replacement.
Since then I have played with Kodi/XBMC, and OpenELEC on the Raspberry Pi. But I am using this much like a Roku box, just to compliment my TV watching. I often wish there was a modern DVR for over the air TV.
Recently when I was shopping the RCA DTA880 caught my eye. A digital converter box with recording. There is also the Ematic AT103B. Both can record over the air TV to a USB stick. This is awesome. Neither however have a network jack, as it would be nice to be able to play back/record to a network share. Another thing I wish it had was line input jacks, so you can record from an external source like a satellite.
Basically someone needs to combine these converter boxes with a Roku boxes for folks who are looking for options when considering dropping cable etc.
The Simple.TV boxes seem closer to what I am seeking as they are able to connect to the network. However they have a portal manged setup, and reportedly a Roku box can can act as a client to connect to the Simple.TV backend to stream live and recorded TV. I haven't found a simple way to use a Raspberry Pi running OpenELEC or what have you to function as a client in a similar way.
The Magnavox HD DVR/HDD 1TB ATSC Tuner has RCA inputs as well as coaxial for over the air ATSC. But I don't really care so much for the price. I'd rather add my own USB drive, so if it didn't have an internal drive, that would help the price a little.