I have been playing about with creating my own base theme which I can use to easily roll out new sites quickly and easily for those who don't want to pay for a bespoke design.
The main problem with this is ending up with one theme for all, to get around this with out having to do any development work is use Drupal's core colour module which allows the user to select the colours of certain areas.
This will just show you the basic code that is required for use with a theme using the PHPTempalte engine with some comments on what the code is doing at parts.
Sorry but I will be using the English spelling, too used to typing with the 'u'.