I would like to see my "I can put toolbars where you never imagined" hack officially part of the core. In inc/plugins/model/_plugins_admin.class.php we see at line 100:

'AdminDisplayToolbar' => 'Display a toolbar on the edit screen(s)',

This hook puts a toolbar above the posting textarea. I propose adding two hooks (and an easy way for a plugin user - not author - to select which of the locations any given toolbar would show up. In my version of that file I have three lines:

'AdminDisplayToolbar' => 'Display a toolbar on the edit screen(s)',
'AdminDisplayToolbarBottom' => 'Display a toolbar on the edit screen(s) under the post textarea',
'AdminDisplayToolbarRtSide' => 'Display a toolbar on the edit screen(s) in the right side column',

Bottom goes under the textarea, RtSide goes on top of the right hand column.

To me this gives The Admin super cool layout powers. The thing I have no hack for is how to make a plugin that would let the user select which of the three locations they want their smilies in.