The script (Maya) lets you color the keyframe's ticks in the timeline.
It can be used to easily organize the type of keys you're working with. You can for example set all your gold key poses to be one color, your breakdowns keys to another, your holds to another... or you could set all your character keys for the spine to one color, the left arm to another, right arm to another...
This video was recorded with the first release of the script, new versions add more features (hotkeys...) and fix some issues (referenced rigs...)
Download last version here : http://www.creativecrash.com/maya/script/colorkey
Please let me know if you find any bugs or have suggestions.