WP is nearly perfect now IMHO, but I would love to see my favorite features from other blog/CMS packages incorporated into WordPress.
From TYPO3 - editable tree view. At the outset in typo, you can define a directory and page hierachy using a folder tree view in the control panel. The entire main menu and sub menu views can be generated before any pages are created, and can also be easily modified.
From phpWebsite - moving boxes around on the page. Sure, you can move things around on all the CMS, but with phpWebsite you get the real time view as you direct them from one spot to another.
From WP - old version link management. Categories are not that important to me, but I really miss being able to toggle link visibility en masse. All of them, ten of them, one of them... however many I choose with one click.
From Website Baker - the cleanest backend interface of all.
From XOOPS - xoops seems to integrate all the page elements into an attractive layout, more easily than the others.
I'm certain that I've overlooked plugins that probably already achieve these actions in WP. If so, my apology. Please don't scold me. In the three plus years I've been using WP, I have found it to be the most bulletproof, easiest to customize, quickest loading of all the CMS I have tinkered with. Also, the search engines seem to have an unusual fondness for WP, even with the default url's.