"Why do Drupal sites always have to look like Drupal", a friend of mine who works in brand development recently asked. "Any time I see a Drupal site, I know it right away". This really surprised me since my friend is usually pretty perceptive about these things, so I wanted to find out why he felt this way and hopefully to prove him wrong.
After looking over a number of sites, I think that what it comes down to is that MOST sites are very similar these days...
Creating mockups of your ideas will make it easier for clients to understand what you are plan to build for them. Its one of the most important phases of any web project - by making sure the client knows what they'll be getting you have a better chance to really satisfy him and also avoid feature creep.
Fusion Drupal Themes has made a useful template of UI components typical to Drupal for Basamiq...