Bookmark: PmWiki | PmWiki / PmWiki
This is an interesting script. I have not installed it or tried it, just browsed through the instructions.
Things that caught my eye:
There is no mention of mySQL or any database needed. I like that. Flat files can be good. All you seem to need is PHP.
You can install this on your home computer if you want a truly private wiki. Or you can install on web server.
Has a plugin type system so you can extend it.
If you add the calendar plugin you get one page per day. You could do a diary or daily journal with that.
Seems to be a very high powered wiki.