[rakoo]

I don't have a lot of information that I need to handle, but I use zim (http://zim-wiki.org/) as a desktop wiki. It's working well for my little needs.

There is also camlistore (http://camlistore.org/) which is trying to be the recpipient for every content one wishes to store: images, music, PDF files, bookmarks, RSS feed items, ... It's working well in the "aggregating" phase, but still a little bit lacking in the "organizing" phase (which may very well be the work of third-party application). For the moment content is accessible through a simple search engine though.