For a variety of reasons, I'm still using version 2 of Bugzilla at work even though it's considered "dead" by Bugzilla. And the interface looks like it's been dead awhile.
Here's the before shot:
Here's the after shot:
It hides the huge header, makes the title of the issue much more prominent and fixes some other formatting nits I disliked. Information that I think is more important is moved up to the top as well. But there are also perks you can't see. You can use the keyboard to do pretty much anything you need to: comment, resolve, browse the URL, search, navigate between comments a la gmail, etc. Once you have it installed, just press ? to see all the keyboard shortcuts.
It's up on GitHub so feel free to fork it and make any modifications you'd like to see.