The coolest thing about the 2600 for me was the "
Secret Mode" almost every game entered if you
switched the power off and on with a short pause in between of
precisely the right duration. Once in the
Secret Mode, every game behaved differently.
The Superman game would let you play as normal, with the exception that you couldn't fly, and Lex Luthor showed up as gibberish. In Pitfall II, you might remember that from the starting position, you can see your friend (Crazy Claws?) underground, but you have to play through the whole game to actually get to him. Well, in Secret Mode, you start the game and instantly fall through the ground like it's quicksand, and land right next to your buddy.
Of course, most games just spewed sprites and sound randomly at the screen and weren't good for much of anything. But the quest to figure out which games had hidden surprises made buying new games all the more fun. Too bad the current emulators can't activate this mode. =^(
Another interesting note:
If you happen across a working 2600 system, but can't find a controller to go with it, all is not lost! Simply plug in a controller from the Sega Genesis system, and play Yar's Revenge until dawn!