Sega is offering a deal through RealOneArcade where you can play free 60 minute demos of classic Sonic games on your PC. The games being offered are Sonic 1, Sonic 2, Sonic 3 and Dr. Robotnik’s Mean Bean Machine. Other Sega Genesis classics are being offered as well. It does require that you install RealOne Arcade however.
Source: *Sega.com*