Michael Pachter's talking about something that's actually kind of interesting. He
mentioned in an interview with NowGamer that Steam's going to launch a service to allow you to trade or exchange your digital copies for a small fee.
Now, we've all borrowed or traded games with friends and that's one of the big things I used to do with the Atari 2600. Since we couldn't afford to buy them all, we would just trade amongst ourselves and rotate the games between a few of us.
Valve's been pretty good at offering up new and interesting features for Steam so seeing the ability to trade games would be a pretty cool option. Even if it's a few bucks to do this, it's going to be worth it for some of the newer titles that you finish off quickly.
To be honest, there are so many damn good sales through Steam that I probably wouldn't use this feature as much though. Just waiting a little bit can nab you some great games for a very, very small price.
Now, if there was an exchange option like where you could sell back your copy of a game for credits, I'd definitely be all over that. It would help on buying those games that can be finished quickly or those that aren't any good and you want something back for them at least.