Jasmine CMS
Jasmine CMS is based on the idea of creating an engine to give the opportunity to use it for a variaty of sites: from blogs to big sized communities. It has plugins that make a nice websitew portal such as forum, image gallery, PM's etc and is easy to code to. Also it is designed keeping in mind to have it as lightweight as possible. As less accesses to the database as possible give the advantage to use it on slow servers too. You can download Jasmine CMS's core and run it as a blog and after that add some features that you like from the plugins offered. It is a very good solution for a blog as well as for a large community site. UPDATE: Jasmine is now on v1.1 a stable one, enhanced with many new features and fixing some bugs from the previous versions. It is a definitely must try!