http://www.cs.cmu.edu/afs/andrew/org/kgb/www/zarf/games.html
Zarf's List of Interactive Games on the Web has legendary status by now, and for good reason--this page is the first place to go if you're looking for stuff to do online. The interaction is mostly with the computer at the other end of the Web, but a few multi-player games are also on the list, as well as some interactive creative writing projects. Each entry has icons that tell you what features your Web browser needs in order for you to play, and some games are described in more detail than others. The list is organized chronologically, with the new entries appearing at the top, which makes it great for constant revisitors, but it might confuse first-time users. Bear with it! Click away, and you'll be surprised how time flies. Zarf's list does not include MUDs and MUSHs.