So I had this idea which is either genius or ridiculous, I can’t tell. There seem to have been some similar requests over the years at Feature request: Configurable safe day coloring. and Feature Request: Color-ratchet.
I was thinking of greatly scaling up my number of goals/graphs. To avoid a sea of similar-looking graphs, I thought it might help if we could give each goal or goal category a “face”, by allowing us to set colour themes for each goal. The themes could redefine all aspects of the goal (background colour, the colours of the different lines, the datapoints themselves, etc.).
Cosmetic modifications seem to be a never-ending cash cow in games, etc. and it might apply here as well. The free version of the feature could include a set number of themes (5-10), while full customisation could be left to paying users.
'ing this because floating ideas like this is absolutely perfect for the forum and others may be inspired to build something like 
at the idea of Beeminder itself going down this 
! I’m especially averse to treating customization like that as a revenue source.