User:Flaarnsturgen/monobook.js

viewSource
This code will create a new button called [view source] to the left of the [edit this page] button (unless you're already editing a page or the page is protected). Technically, it takes you to editing the page, but removes the interface (edit summary box, minor edit and watch checkboxes, save/preview/show changes buttons) below the editing box. This will prevent you from accidentally saving the page if you were just playing with the content.

To install it, add the following to your monobook: