BeyondTV: This is great software
The previous version was pretty good overall, and works great with the MPEG capture/tuner card I got with it. The new version just feels a little more polished in terms of UI and features. The "smart skip" that finds commercials and allows you to blow passed them with one click on the remote is awesome (I have the Firefly remote, which they also make). They have an affordable package that includes BTV, the capture card and the remote. They also have cable kits to control DirecTV receivers.
The .Net connection: The Web-based admin is ASP.NET based and can be modified.
I was skeptical that I could build a PC that really just worked, using nothing but the remote. Aside from ITunes, it basically does work with the remote, and that's all I need. All DVR and DVD functionality is accessed via the remote in a manner that's as simple as using a satellite TV tuner. It has really changed how we watch TV, and I'm curious to see how this phenomemon forces broadcast television to evolve. Bandwidth for true on-demand video isn't there yet, and broadcast isn't going to shrivel up and die overnight (well, radio might, since it sucks anyway).
I love good software. I wish there was more of it.