So, the colour scheme I'm currently on is:
Stable colour for the header: #1856AB
Colours designating user location (directory or thread)
- Directory (forum/subforum): #3B8BF8
- Thread: #AB7307
Areas of user input: #F8B73B
Components such as the breadcrumb colour and the colour of the left buttons is dependent on whether you are browsing the forum/subforums or if you are in a thread, as does the colour of the "New Thread"/"Reply" bar at the bottom (above the user input).
Unfortunately I've only had time to fiddle with the colours today, but still, progress of a sort and you are absolutely right, Kroc -- I hadn't taken the time to think sensibly about what I was meaning with the colours.
https://dl.dropbox.com/u/2477024/metro-screenshot-09.08.12.png