I keep following this post and I get overwhelmed trying to keep my favorite tweaks intact while surfing different themes to fit my mood (am I the only one who can’t stick with just one theme?). Every time I switch from 80’s Neon to Moonlight or Cybertron, for example, I have to re-tweak the code for those CSS files and do a lot of trial-and-error. Obviously this isn’t mission-critical, but there are certain tweaks that seem to have wide support. Maybe a basic version of each can be made into a plugin?
Alternatively, maybe the CSS tweakers community can decide on a standard format and comment-out the parts we don’t want to include in our custom themes, but leave them there as optional? A template of sorts? I think @Boyd 's Traffic Lights theme goes a good way toward this already, with optional tweaks at the end but standard stuff clearly labeled along the way.