If you're over the age of 20 and can afford to lose a few hours today, check out RGB Classic Games. The website plays host to over 300 DOS games emulated via the magic of java, so you can just play them in your browser. Apparently all the games - including such absolute treasures as Earthworm Jim - are "freely distributable because they are shareware, freeware, or because the copyright holder has officially and legally released all rights to the public domain (abandonware)". Nobody tell Pat about this.
Thanks, PC Gamer.