I'm looking for a personal wiki that can be installed on an usb stick and (more importantly) somewhere on the cloud (dropbox). I've looked at the Wiki Matrix, but I really don't care that much about any of the options, so I end up with a choice between ~50 wikis at the end. Tried out TiddlyWiki but there are some things that really annoy me like the fact that all pages get opened on the same page. It really looks like it'd turn into a giant mess pretty quickly.

I'd like to have something that's pretty close in terms of appearance and usability to wikipedia. Hierarchical categories for organization would be really nice. And accessible storage (in case I ever want to convert it to something else).