Like most serious wikis, MoinMoin automatically saves page revisions. You can easily compare revisions, even if you don't have permission to edit the page or revert it to a previous revision. MoinMoin also has a vibrant market of extensions and themes, although if you're looking for a wiki with dozens of themes, you might be better off with DokuWiki. As it stands, I counted ten themes on the official MoinMoin Theme Market. Not a staggering variety, but you can always make your own.
Unlike Tomboy and many other personal knowledge management solutions, MoinMoin can easily support multiple users. You can start off by using it on your own, and when you need to collaborate, simply expand it to include your colleagues. MoinMoin may lack the pizzazz and intuitive simplicity of a desktop application, but it is a sturdy, professional wiki.
Note: The download link take you to the MoinMoinDownload page, where you can download the latest version and read installation instructions.