I have a better(?) idea.
How about we make the whole site style-sheet compatible, and have an option in user settings to specify a location & name for the stylesheet, that way everyone can personalize their own theme, without too much carp being added to the server.

update: How's this for clarification:
In user setting, where you specify what theme you want, you have an option to choose a style-sheet version of the site, with the option of specifying a location for the stylesheet.

"cRaZy is co01, but sometimes cRaZy is cRaZy".
                                                      - crazyinsomniac