In the interest of sharing, I'd like to provide my current list of working emulator sites for various platforms. All of these enable gameplay directly within your browser, so there's no sticky business of downloading software and finding the necessary game files to get it all going. These are all great sites and we should all show our support. I'm dubbing this the "November 2009" edition of the list and would love to keep adding to it, so suggest away and when I do the next edition, I'll expand it. Here goes:
* 2600online.com - Play various Atari 2600 Video Computer Systems games
* c64s.com - Play various Commodore 64 games
* Freearcade.com (Scott Adams section) - Play various Scott Adams/Adventure International text adventures
* JEMU - Emulate and play on the Acorn BBC Model B, Amstrad CPC464, Dick Smith VZ-300, Sinclair ZX Spectrum 48K, Sinclair ZX80 and Siclair ZX81
* nintendo8.com - Play Nintendo Entertainment System (NES)/Famicom games
* Play Infocom Adventures Online
* The Gallery of Zork - Infocom museum and plenty of games to play
* Sandy White's Ant Attack
* Sarien.net - Play Sierra adventure games
* SC-3000 Survivors - Play Sega SC-3000/SG-1000 games
* Virtual Apple ][ - Play Apple II and IIGS games
* vNES - Play Nintendo Entertainment System (NES)/Famicom games
Finally, don't forget the Games section right here on Armchair Arcade. Enjoy!
For Timex TS1000 / Sinclair ZX81 I have the following website bookmarked.
Primarily an information resource, there's over 500 ZX81 programs (the majority with their cassette box inserts images too) that can all be played via the browser using something called a JtyOne emulator applet. Or if you've got the real thing you can download the binaries to play on your ZX81. The emulator even works with the high res games.
Atari.com has some playable games: