One of my HD tvs PIP and I used to use it all the time for 2 sports games, but I just got a bigger tv for the livingroom and it doesn't have it.
I miss it! When I subscribed to cable, I used to hook my cable DVR up to one input and then use a coax cable from the wall to my tv for digital cable. And then the PIP feature would work because the wall cable is a seperate input.
I ditched the cable company and went to Roku. So, now with the Roku, there is no true PIP, but here are a few ideas to help toggle:
1) If you have a tv with the PIP function, then use your Roku as one input and the wall cable digital over the air as your 2nd input. A clear picture may involve buying one of those antennas that you have to stick to a window if you don't subscribe to digital cable.
2) Buy 2 Rokus and put them both on one tv under seperate inputs. Then, choose a show on one, toggle to the other input and put your other show on that one. Then, you should be able to just toggle back and forth between inputs. It might still have to buffer each time (I haven't tried this idea yet), but it's better than changing shows within one Roku. Much less clicks!