Neo-Portal is an interesting project. It seems clean and mature in some way, and rough and childish in others. Here’s a blurb from it’s freshmeat page:
neo-Portal is a data presentation and delivery system. When data is output in DHTML, it behaves like a portal. It features full i18n localization support, OS, Web server, and database independence, support for WSDL Web services, and output in XHTML, PDF, RSS, TXT, RTF, WML, and more.
It’s interesting. It looks like it has a plugin interface that can do some cool things, but it doesn’t look like every other portal/CMS, which is a good thing. I haven’t installed it, so I don’t know how customizable it is, but if it lives up to its specs, it could be quite useful. There is also a lot of information on the project’s SourceForge page.