Pile of links to some old/classic online games.
This is just a dump of an email with some interesting links. I haven't explored all of these.
Many are simple enough to be shockwave or flash.
80's arcade games online
Nintendo games (need PC emulator) http://www.tripletsandus.com/80s/80s_games/nes.htm
Yahoo games http://games.yahoo.com/
Browser based games directory
http://www.games.com (online board games, arcade games, card games.)
http://www.rubiks.com/ rebiks cube games and downloads
http://www.realonearcade.com/ online archade games includes some old sega games
http://www.arcadegamesonline.com/ cool shockwave games..darts bowling 8 ball air hockey sking. Bball, all different categories.sports, adventure classics, strategy, even "CABLE MODEM VS DSL!" even movies!!)
http://clevermedia.com/arcade/ more shockwave games.really cool seasonal games even a game called "make your own game!" Tons of variety.
Few selected list of Shockwave games:
Home Run Derby: http://www.baberuthleague.org/shockwave.html
Home Run Rally: http://www.candystand.com/games/cs_shock_cshr.htm
Ball Park Blast: http://www.candystand.com/games/cs_shock_csbb.htm
3D using Havok: http://homepages.nyu.edu/%7Ecd293/Apache.htm
3D using Havok: http://www.pictofun.de/zong.htm
First-person shoot them up
lemonade stand math
Java applet: http://www.coolmath4kids.com/lemonade/index.html
space invaders: http://www.tripletsandus.com/80s/80s_games/invaders.htm