Here's a novel concept: digital delivery store Direct2Drive is trialling an offer whereby PC gamers can download and rent a game.
It works like this: you download the entire game from D2D, and pay $US5 for five hours of playtime. If at the end of that time you want to buy the game, you pay the difference from its retail price. We're unsure as to what happens if you decline that offer - presumably the game is "locked" - but we'll check with D2D to find out.
Neat idea. Sadly, only four games are currently being offered as part of the deal (Silent Hill: Homecoming, Grid, FEAR and Divinity 2), all of them older games that you should be able to buy in full for not much more than the renting price, especially if competitor Steam is saving a sale.
Apply it to recent, full-price games, though, and this becomes a great idea. An asking price of $US40-50 for a PC game can be steep if it doesn't have a demo, so having the chance to try before you buy could help a lot of uncertain gamers out.