I just ran into something interesting on BitTorrent: a full suite of Tycoon games there for the downloading. Only it's not quite what you think: the downloads are time-limited trials. After 30-60 minutes you get the opportunity to pay by credit card for the whole game.
Online distribution isn't anything new, but this is the first time I've seen it work so smoothly. Trymedia is the company behind this. Their ActiveMARK suite includes DRM, distribution, and payments. At $20 a game, maybe they'll make this work? A quick check suggests that a crack for the DRM is not widely known. Trymedia's survey suggests that folks who steal games by downloading them would be willing to pay for them if the terms are right.
The main site for this distribution channel is Trygames. The games there are generally second tier and/or old. I don't know if Trymedia seeded the Tycoon bittorrents themselves or the publishers did. Atari/Infogrames, one of the main Tycoon publishers partnered with KaZaA to distribute ToEE awhile back.