For those looking to plan out a WordPress site before actually opening the admin screen, checkout the tool JumpChart. It allows you to create wireframes and mockups, collaborate with other contributors, build the site with a quick sitemap view… and all with version control. The best part for WordPress users is the ability to take what you have developed and export right into your WordPress site. Check out the details here. If you are looking to develop many sites that involve distributed collaboration, this might be a system to check out.