Jonathan Nowacki wrote:

I would like to create an extension that will allow you to add a buttons to the edit window. Right now there are:

• Bold
• Italics
• Underline
• Hyperlink
• Headline
• Image

and other buttons. Any advice on how to go about adding more features to the edit toolbar?

You can just use javascript at Mediawiki:Common.js as many wikipedias do.