In-browser page editing
Here's a neat JavaScript trick that makes a web page editable. It could be used for adding/deleting filler content to see how the page layout looks; helpful for front end developers. Not sure if Firebug has it implemented already.
- Open up the webpage you want to tinker with.
- Copy and paste the following in the address bar of your broswer and hit enter or click go.
javascript:document.body.contentEditable='true'; document.designMode='on'; void 0
Source: http://azure.ironie.org/291-edit-any-web-page-in-a-browser