"This collection contains selected historically important software packages from the Internet Archive's software archives. Through the use of in-browser emulators, it is possible to try out these items and experiment with using them, without the additional burdens of installing emulator software or tracking down the programs. Many of these software products were the first of their kind, or utilized features and approaches that have been copied or recreated on many programs since."

Internet Archive: https://archive.org/details/historicalsoftware

http://blog.archive.org/2013/10/25/microcomputer-software-lives-again-this-time-in-your-browser/

[Update]
http://www.zeit.de/digital/games/2013-11/games-klassiker-archivierung