Atari
Atari was formed in 1972, originally producing the coin-op Pong
and came to an end as a hardware company in 1996.
They released the Atari VCS (aka Atari 2600) in 1977,
Atari 400 and 800 8-bit computers in 1979,
Atari 5200 SuperSystem (based on the 8-bit computers) in 1982
and the Atari 7800 ProSystem in June 1986.
It was actually ready in 1984 but Atari changed ownership that year
and it's release was shelved


8-Bit Cartridges
Pictures (Small)
Pictures (Medium)
Screen Shots
Cartridge List
Pic List


5200 Cartridges
Pictures (Small)
Screen Shots
Cartridge List
Pic List


7800 Cartridges
Pictures (Small)
Screen Shots
Cartridge List
Pic List


Info
This collection has been gathered after many hours of trawling the internet
and a lot of help from the Folks at the AtariAge forums.
I guess a picture of a real cartridge confirms it's existance!
Thanks to the following great sites in particular:

Atari Age
Atarimania
Puisoft Cart Collection
Fandal
Atari 8-Bit Forever
Atari Protos
AtariGuide
Cartridge Dumping Project
Andrew Kriegs' List (v5.9)
ebay
Atari7800.org

If you have any missing bins or pictures to help complete the list please email me.