Internet Explorer 9 tips for power users from Microsoft itself
There are four categories at the moment -- Faster ways to get to your websites, Top keyboard shortcuts, Change and manage search providers, and Manage add-ons -- and there's also a good resource of videos that can walk you (or a newbie friend) through IE9's core features.
Most of the 'power tips' are fairly light on details at the moment -- the keyboard shortcut page only has seven shortcuts! -- but we're sure, by the time the browser is released, that it will grow into a sizable and comprehensive resource, just like the Windows 7 pages.
In the meantime, you'll learn more from reading our IE9 guide.