Open Source Community Technology Package

Does anybody have a recommendation for an open source community technology package?

We need something that provides for content management, integrated wiki, integrated forum (which sends email digests, frequency use preference driven), blogs, etc.

Ideally the technology would provide for the above elements to live in their own place within the information architecture, but also be contextually "threaded" throughout the experience. For example, if content is posted and there are relevant blog entries, or forum discussions elsewhere, they could also be featured on the page as keyword feeds perhaps.

Also ideally everything would be componentized enough to provide for a seamless user experience, where the technologies are pulled into a visually designed/custom developed overarching framework.

Also ideally, the technology components themselves would be skinnable via CSS, etc

Any help is greatly appreciated!