[Mad]

Hi,
Has anyone done this? Like a little drop-down box when the user registers letting them choose a skin for the site. It sounds pretty hard, but I'm willing to work. Where and how would I start?

[edit] Perhaps it would simply be easier if the skins were available to all users. But I just need the logic behind this. Like 4 pre-defined options, each loading a different CSS file, and a non-expiring cookie so that setting would be remembered and they wouldn't have to choose the skin everytime they visit the site.

Thanks in advance for any help I can get on this!