Editing Drupal Hospex Features (section)

== Customized pages and forms ==
Sometimes we want to have a page or a form (such as, user profiles, or a signup form, etc) almost exactly like it is delivered by Drupal + contributed modules, but we want to change some tiny bits: For instance, add an option to the signup form to sign up for specific groups, etc. Or disable some fields. Or, split the profile page up to several different pages.

Luckily, this is all possible by creating custom modules! You can grab the data for generating a form or a page, modify it, and let Drupal render the modified form. Or you can intercept the usual process of rendering a page, do your modifications, and give back to Drupal to do the rest. The nice thing is, you only implement what you want to change, and leave the rest to Drupal core + contrib.

And of course, you can theme every bit of a Drupal page. You can even do a lot of the above mentioned customizations with themes alone, but beware! This can bloat your theme and makes it hard to provide alternative themes.