In Softimage you have different colours that helps out when you are working with keyframes. Red= you have keyeframed the attribute and the current frame is keyed. Green= The attribute is keyframed but there is not a key on your current position in the timeline. Yellow = There is a keyframe on your current position in the timeline but you have changed the attribute compared to the keyframe. Please add something similar.
Even though its not exactly what you asked sonictk, but theres a way to actually make the Keys on the Timeline have diferent colours. Doesnt need any special plugin its on Defult Maya.
Its called the Special Thick Key, you can change its colour in:
Windows---Settings/Preferences---Color Settings---Animation
In there you change the Color of the TimeSlider tick special.
I changed mine to Blue (as in breakdown)
Beware of the Time Slider Breakdown... its not the same and I advise you not to ever use it 🙂
Theres also a script that allows us to have a lot of diferent colors on our Keys, but it creates that info as well on the Graph editor:
http://www.creativecrash.com/maya/script/colorkey
Well we all have or own workflows, I always Key EVERYTHING 😛
Dont care if Im keying things im not even using, ill clean them up later 🙂