I'm try to keep the count of 3rd party plugins as small as possible.
Legend: - necessity is under question.
This is the biggest addition. DokuWiki always sort topics by alphabet, but when writing documenation very frequently needed custom sort. This plugin give ability to sort topics and namespaces in different ways.
Page index in current namespace.
{{indexmenu_n>1}}
Allow to add HTML style comments. They are not visible in page. This plugin uses the same syntax as regular HTML.
<!-- comment -->
For certain complex tables (menus) used this plugin. But instead those rare cases I strongly discourage to use this plugin syntax.
Quite useful plugin, adds entity. Syntax - backslash with space followed.
Extended list syntax, allow paragraphs in the one list and adds defitinion lists.
Add abitilty to set text solor.
Allow define global substitutions.
Plugin allow define fields and reuse them in text (just like above, but locally on page).
This is admin mode plugin for export DokuWiki as plain XHTML pages. This will be used in near future for generating offline version.