List of simple extensions

Beginning developers may wish to watch this intro video and peruse the list of simple extensions when considering how to create a new extension. Some of the code from these extensions can provide insight into how to approach an implementation task, or even be cannibalized for your purposes.

License
You may want to include a licensing statement at the beginning of your extension file, e.g.:

Extensions

 * Example extensions
 * ContentAction: An extension that demonstrates how to use the SkinTemplateContentActions hook to add a new content action.
 * ErrorPage: Example of the page that uses extensions hooks DBConnectionErrorRaw and DBQueryErrorRaw for making nice error page.
 * Example: This is an example extension. It doesn't actually do anything useful, but can be copied to provide the basis for your own extension.
 * MyExtension FourFileTemplate: Four-file special page extension template.
 * HelloWorld: A special page that says "Hello World!" in the appropriate language.
 * Parser_hook: A parser hook example, use it on a page like
 * Variable_hook: An example parser hook that defines a new variable,


 * Manual:Special_pages provides an example of a four-file Special Page extension called  that outputs "Hello world!" Don't forget the standard collection of special pages in includes/specials, the functionality of some of which you may already be familiar with.
 * Assert Edit is a simple API extension.
 * Awesomeness is a simple API and ArticleSave extension.
 * BreadCrumbs (Kimon), which uses UserToggles, provides a good example of how to incorporate CSS files into your extensions.
 * PatchOutput uses the OutputPageBeforeHTML hook to apply some patches to the HTML code of a page before it is displayed
 * RemoveRedlinks uses the LinkBegin hook to turn all red links into regular text.
 * Extension:ChangeSessionSkin allows to switch between skins for the duration of the session, or until changed again, without changing the user preferences, thus available to anon users too.