For those with a Harmony cart or simply using emulators to get their 2600 gaming on ROMHUNTERS archive is an excellent presorted and organized archives. Seems for the New Year he has just released v12 of his awesome collection.
Follow this link to Atarimania to download the archive!
Here is the description from the site - Atari 2600 VCS ROM Collection
Having been an avid Atari 2600 game player in the eighties, I was more than happy to discover that the games I used to play as a kid could be re-experienced on my PC by downloading the proper ROMs and playing them on an emulator. For me, it was like finding back little bits of childhood memories and the main reason to start "hunting" ROMs on the Internet.
But while collecting, I noticed that many ROM sets on the net contained bugged .bin files (the so called "bad dumps") and that many ROMs carried incomplete names that often lacked the correct game information.
In order to give these ROMs their proper names, I started studying the games they belonged to. That was the moment I entered the amazing world of the Atari 2600 and also the beginning of a new "hobby".
I found out that, although there were only a little more than 500 different games made for the Atari 2600, almost all of these games were re-released many times, in many forms, under many different names and by many different companies, creating an incredible range of more than 10,000 different cartridge releases (of which more than 8,000 are now archived in our database).
While working my way through fifteen years of VCS gaming history, discovering all kinds of strange and funny looking "pirates", never released prototype games, interesting background stories and fascinating label artwork, I gathered an enormous amount of information which I systematically tried to cram into these filenames.
Now, after almost ten years of collecting and researching, the result of all this work can be downloaded below. I'm very proud to present you my personal Atari 2600 ROM collection here on Atarimania and I truly hope you will enjoy it as much as I do.
Please don't let the long filenames scare you off. You'll get used to them and trust me: they form an excellent source of Atari 2600 game information, which can be very useful for any serious Atari game collector and fan.
In short: if you're looking for an ordinary Atari 2600 ROM set, look elsewhere. It can be found almost everywhere on the Internet without too many problems. If you're looking for the most genuine and best documented Atari 2600 ROM collection in the world, then look no further: this is the place to be.