DRUPAL

Drupal is an extremely flexible and tightly-coded CMS, great for intermediate to expert Web users, and is often preferred by advanced developers who want the ability to completely customize and control their CMS. Drupal tends to have a steeper learning curve than most CMS apps, but yields a greater pay-off in terms of flexibility. The Drupal framework can be used for all different types of Web sites, ranging from community Web portals, discussion sites, Intranet applications and social networking sites to personal sites, blogs, corporate Web sites and more.

MAMBO

Mambo has been in development since 2000, and over those years, has garnered almost 8 million downloads--making it arguably one of the most popular CMS's in the world. The core code base of Mambo is very similar to Joomla's, as Joomla development started when a group of developers split from Mambo in 2005. In general, the two CMS applications are very similar; the main difference lies in a larger Joomla following, resulting in more rapid development of the core software and developer extensions. Both Mambo and Joomla market their products as "out-of-the-box" Web site solutions; however, both applications are recommended for intermediate to expert Web users.

E107

e107 is an advanced CMS system, preferred by developers who are looking for a solid core, easily modifiable themes (if you know some PHP!) and an extensive number of plugins. The software is recommended for intermediate to advanced Web users.