Runtime Wiki is an easy-to-use desktop wiki written in Java. Runtime Wiki is a wiki-like program that works with local files.
Runtime Wiki is a just a very simple implementation of such a program and supports plain text files (suffixed with the .rtwiki extension).
Runtime Wiki will ask for a file or directory. If you are going to create a new wiki, create a new directory and select it from the dialog.
If not, just select the directory that contains the .rtwiki files (selecting a .rtwiki file from that directory will also work).
Also, if there is a wiki folder at the same place from where Runtime Wiki is executed, that wiki will open automatically.
Runtime Wiki is cross-platform and it works on Mac OS X and Windows. Binaries for the Windows platform are available on the project's homepage.