If you are looking for a fast & lean CMS, this is a great choice. Tiki, XOOPS, Mambo, and the rest all have their place, but for great flexibility & performance, consider Drupal.
I like the templates with some of the other CMS systems better, and the documentation isn't as good as it can be, but its very easy to understand once you dig into the drupal.org site.
Note that I had no problems with installation.
Very interesting project
I have found drupal to be a very interesting project. It is easy to set up and only requires MySQL and PHP4. It's modularity enable you to add or remove features easily. The develloper community is very friendly and has even incorporated ideas by innocent bystanders.
An open, cross-platform journaling program.
A scientific plotting package.