One of them is Word 2007's little on-the-spot editing toolbar, which is officially known as the Mini Toolbar. Perhaps you've encountered it: It appears when you highlight some text and then move your mouse up.
Admittedly, it's a handy addition, but as someone who's literally spent 20 years mousing his way to the top of the screen for font selection, highlighting tools, and the like, the Mini Toolbar strikes me as a Maxi Annoyance.
Fortunately, it's easy to turn off: Click the Office button and then choose Word Options. Clear the checkbox from the very first item: Show Mini Toolbar on selection. Click OK and you're done. Want the toolbar back? Ah, you don't really need me to explain that, do you?
Hey, here's a question: What feature(s) do you like most in Office 2007? And what feature(s) do you like least? I have no real reason for asking other than I'm curious. And I'm not a cat, so I feel fairly safe in being so.