The only reason I'm adding my request is in the hopes that Morotola is monitoring this forum. I have the same issue ... 5 email accounts. Tying the right color to a given account will make the world much easier.
The colors are assigned in sequential order. There are about 20 different colors. I have not found a way to change the color during the account setup. However, if you delete the account and set it up again it will give you the next color in the sequence. Continue doing this until you have the color you want. Yes, it's a PITA.
Not sure about the gray ... the email I'm refering too is the standard email within the Droid (not Gmail).
By the way, after the 10th or 12th time reentinring my email addresses, I actually wrote down the color sequence. For anyone who cares, its:
Green, Dark Light
Green, Bright Light
Green, Med Light
Green, Medium Dark
Purple, Dusty Light
Blue, Dusty Light
Purple/Blue, Dusty Light