This isn't a plugin per se, but I'd thought I'd share a novel combination of plugins I'm using to achieve a nice effect.
I combined the WindowDrawers with the Ext.ux.Wizard and it provides a convenient way to embed a "help drawer" for each page of a wizard without obscuring the options.
Also, the help drawer I use, is also a MediaPanel that loads the help page from a URL.
The user can open the Help Drawer which describes the help for the page of the wizard they are viewing.
if they leave the drawer open and continue to page through the wizard, the help page updates.
There's really no extension coding here, its more or less combining these to suite your needs.