!!! Introduction
It's common for people to use a wiki and some discipline to replace a more complex application. They can add some plugins to make it easier.

It would be awesome to be able to program extensions of a wiki inside the wiki:
* integrated revision control
* low barrier to entry
* programming on the web

!!! Related notions
!! Existing plugin mechanisms
! Confluence plugins
The Confluence wiki allows for a lot of [different plugin types|http://confluence.atlassian.com/display/CONFDEV/Confluence+Plugin+Module+Types]
! JSPWiki plugins

!! Scott's wikitools
Scott just started some work on wiki extensions that allow to access the wiki from outside and that make use of templates [Wiki Tools]

!! Databases

Most applications need to store data and often use a database. It's common to store large amounts of data on a wiki with a repetitive text format. This is in effect a primitive type of database that tends to mix data and its presentation.
Plugins can be used to allow access to a database from a wiki page ([Database and Wiki])

!!! Use cases/Applications
!! Elementary use cases
! Text to graphics
It would be nice to be able to input some parameters and information and obtain a graphical representation. This can be achieved for certain graphical representations with Java JSPWiki plugins (e.g. [ImageGen Plugins]). With a template engine, [SVG|Wiki and SVG] and some Javascript, we could probably create new similar plugins from the wiki.
! Data sheets
It would be nice to be able to create a simple database application simply by following some conventions (e.g. type JSON code or maybe wiki lists with key,value pairs) and then be able to perform some operations on it:
* render a template with values taken from a data sheet page
* search for pages with a certain key having certain values
The Weblog plugin of JSPWiki is an example of this type of application 

! CGI wiki pages
CGI scripts (and other dynamic webpages) can set their output mime type and generate content on the fly. The wiki engine could have a new .jsp page that runs the regular page through the wiki engine without all the skin information and lets the page set its mime type.
This would allow users to compose multiple such wiki pages simply by referencing the URL. This is very much like attachments and it might actually be seen as a special case, so the wiki tag for attachment could be reused.