http://www.digitpress.com/eastereggs/cvdonkeykong.htm

Has anyone managed to successfully do any of the special easter eggs for the ColecoVision version of Donkey Kong? Supposedly, these easter eggs have only been verified on the actual console version of DK, but not yet in emulation. And don't forget that there were two versions (24K and 16K), so these easter eggs may not work on both versions.

The ones I'd love to see work include:
Start at Level 5 (8000 points time bonus): press # and 9 simultaneously.
Start at Level 6: press # and 0 simultaneously.
Start at Level 7: press 0 and 9 and then #.
Elevator Screen - Fall Through Metal Floor: bring Mario to the top right corner of the elevator screen by where the Purse is, and guide him on the short ladder rocking your joystick up and down.

~Ben