You should make your orange buyers sign a pact that they really bought those oranges from you, and give them an activation key written on a piece of paper that they must read out loud on the street, if they want to eat the orange in public. Of course, they might just go home and eat it hiding from everyone, but that's just weird.
Another method is genetically mutating the skin of the orange so that the buyer is only able to peel it off when he/she shows the skin the pact you signed at the time of buying it, proving it's your orange. Then you can always add another mutation that will let them eat their orange only if they are calling you on the phone and stay "online", and if the battery runs out or they hang up the orange will disappear to the 9th dimension until they recall you.
This way you will make your past buyers come back, and definitely make sure your faithful costumers will remain faithful to you, by making their purchase easier and safer, right?
In all seriousness though, I'd second and improve the idea of demos altogether. Demos shouldn't be like only one or two levels long and without multiplayer. It can be deceptive in both ways. For example, the demo for Sanitarium suggested that it was an oldschool point-and-click horror game. But upon buying it, I realized that it's more like a game that messes with your mind, and only has that one creepy level altogether that was in the demo. Of course it had some creepy elements afterwards, but it wasn't trying to be a horroristic game like the demo said, but more of a David Lynch-like gaming experience. The demo targeted a completely different group of costumers than the ones that would have been really interested in it.
I think having longer demos than a few levels should really help the industry, and they should also include some multiplayer. Example: Call of Duty series. I'm not sure if their demos actually have something like this or not, but why not have a multiplayer in the demo that 1) lets only 4-8 people play in a map at maximum, 2) have only one level with full player count, or 3) give access to multiple or all levels with full player count and give a 2-3 hours time limit for the demo.
As for the singleplayer part, I'd say a drastic change should help a lot, like letting half of the SP campaing be played in the demo, or if it's a more time consuming game (i.e. Final Fantasy XIII or L.A. Noire) then let them play through roughly around the content of the first disc (thinking of Xbox measuring here). Just imagine if you played a demo like this for the first time for, say, Heavy Rain. Will you be more interested in buying it if you only played like one scene for each character, or if you played a good big chunk of the game which ended with a cliffhanger? A perfect example for this was Limbo.
Some good ideas for demos are also the Trymedia service and the demo for Microsoft's Midtown Madness 2. The first let you download any full games for free, letting you try them for an hour. An hour can make all the difference for some smaller or shorter games, but some should have even 5 hours to be able to judge it. That's literally the only problem with the service. The second had a trial that set you a timelimit again, but after each time limit you could play the game again, but the draw distance kept coming closer to your car, until it devoured the whole screen and all you saw was your car. Use this last mechanic and remove the trial time limit (and the fact that it only had one environment and one controllable car), and you got yourself a demo that will make some people want to play your game for more than just say, an hour or even half.
Anyway, that's the only constructive thing I could think of that would help bringing costumers to rather download a bigger part of the game from the developer/publisher, as it's not as risky as a pirate download of a full game, which may or may not contain some trojans. Of course it would not cause piracy cease to exist, but those who are helping themselves to games for free for the heck of it will always do so; not because of the money or the DRM, but because they are dicks and they feel better as pirates.
