Our organization needed a wiki system for internal I.T. documentation (runbooks, code snippets, etc.) We tried a number of other wiki systems before settling on Dokuwiki -- Confluence, MediaWiki, VQWiki... the list goes on.
Even though I try to avoid PHP apps as much as possible -- as their average quality tends to be questionable -- Dokuwiki turned out to be a perfect fit for us. It has exactly the range of features we needed (LDAP authentication, syntax highlighting, etc.), it was super easy to set up, looks good right out of the box, and is just an all-around well engineered system.
I'd highly recommend this, especially when you want a solid all-around wiki solution that fits well in the context of a larger organization's I.T. department.
Working self-employed i need a fast and easy-to-manage solution for my business homepage. (I teach game programming to kids, see http://www.spielend-programmieren.at )
Having played around with static html, mediawiki, joomla and other CMS systems i found out that DokuWiki is exactly what i need.
Easy to maintain, easy to update, mountains of plug-ins and themes, easy to backup (plain files, no database) and fast enough for my needs.
The wiki syntax is so easy to understand that i teach it to children (before teaching HTML). And you can include html code into the wiki if necessary.
Nice community, forums, and the main developer Splitbrain to chat in dokuwikis irc channel.
Thanks to the plugins, setting up a multi-lingual site is very easy.
Thanks to the simple user management, i can give each student it's own wiki-namespace (including multilingual namespace!)
Thanks to the very clear (plain file!) internal structure, reorganizing a Dokuwiki is a simple task.
But be warned: Dokuwiki will spoil you ! If you are used to Dokuwiki and have to work with other things like WordPress or RST you will find them ugly and annoying.
There are a many many programs from which demons seem to spring as you learn more about them. Things don't work like they should, or like you want, or at all, and a part of you dies inside. Good software, in my book, is the small subset of programs that has no such dark secrets, no unfortunate surprises.
DokuWiki falls into my category of great software, that not only works as it should, but often brings happiness to your day by working beyond what you would expect in often small yet extremely helpful ways. I have yet to discover a design decision I disagree with.