More accurately, I wish someone would create a Pandora for Game Demos. It could be a third-party application, but the purchasing process would be awkward (as Pandora’s is). Ideally, a platform holder would create this, and it would be integrated with their store.
A console could do this for their downloadable content. Steam or Desura could make a home for it on their platform. OnLive, such as it is, could do something like this. Since I know the mobile space and its paradigms best, I took the liberty of drawing up some wireframes of what it might look like if Apple, Google or Amazon made their own Pandora for Game demos.
Lobby
You enter the app (or subsection of an app), and it urges you to make a new channel based on a game you enjoyed in the past. If it were done right, that particular game wouldn’t even need to be available on this platform. It would dump you right into the demo for a related game that is.By demo, I don’t necessarily mean that the game requires a specifically-created demo. It could be simply a time-limited session of a game in it’s normal form.When you pause the game (or whatever the equivalent of pause is for this particular game - going back to the main menu perhaps). The game screen would shrink, revealing a border, allowing the player to skip, rate, or buy the game they’re playing.
Pause
After the demo or play period is over, the game screen shrinks again. At this point it might transform into an advertisement of some kind, with the ability to proceed taken away for a short period of time.It's not a fully fleshed-out idea. There are some major decisions to make and hurdles to overcome. First, there's the technology problem. Downloading a game, or fragment of a game, takes a while. You could stream the games, as OnLive does, but unless you are OnLive, that's a big peice of technology to build for an unproven concept.It's been pointed out to me that this might not be great for game creators. Pandora pays the artist and publisher for every time they play a song. What do game creators get here? This is all speculation, but I think the answer is, "higher sales." 
End
For big publishers with big games, that speculation may not be worth the risk. However, game creators regularly put out game demos which they hope to get in front of as many people as possible. Increasingly, games are free and have in-app purchases. Many games are available in free and paid flavors. For these developers, I think they have everything to gain and nothing to lose.What does the platform get out of the deal? Same answer (plus perhaps a little ad revenue on the side). More sales means more for them, too. It also helps alleviate the discoverability problem we all rail about. Have any of you discovered new artists or music using a service like Pandora or Spotify?
