Some of my site users prefer a light theme, others prefer dark one. In drupal 6, is there a way to allow users to choose their favorite theme? How? Thanks
Try Themekey module. After installing this module from 'ThemeKey User Profile' configuration, enable the option for user to select their own themes, so that it will be available in user profile and user can select their own themes.
I am also convinced with Switch Theme module. It provides a dropdown created in a block that provides option to choose any of the theme enabled from the backend.
So you just need to enable themes from backend that you want to show users to switch.
Hope it will help!
I just found Switchtheme, which will give you a block that allows users to switch.