I am wondering if anyone uses some sort of a Wiki in their work on fictional worlds, especially if the world is wide and complex, and the dramatis personae list is rather long.

I know some old-school folks are still using index cards (disclaimer: I am using "old-school" in a perfectly neutral sense). Which is perfectly fine, I can understand the mechanics behind that, and the charm of the tactile feeling.
But - to each their own.
I am more of a digital guy myself, and prefer the convenience of quick search (and occasional replace), as well as the ability to cross-reference articles via hyperlinks.

Hence, the question is: if anyone here uses some sort of a computerized Wiki to catalog and keep track of the characters, cultures, history and geography, etc., what kind of engine / software do you utilize?