You will need to install a user script manager extension to install this script.
The MTurk dashboard doesn't make good enough use of the available screen space for my taste, so this script modifies the layout a bit.
This is just a simple CSS patch that overrides some of the layout styles. It'll probably break whenever they update the dashboard, but I'll fix it as soon as I notice that it's broken.
It works nicely for my dashboard but I can't promise it'll work for everyone. It works with Dashboard Enhancer as far as I can tell, but I don't regularly use it so I won't know when/if it stops working with it.
Check the screenshot below to see how it looks (current version looks slightly different but you get the idea).