Show only one preview per window
I have been struggling to find my tabs every since IE8 decided that abusing the fancy new Win7 window preview feature was a good idea. I use the order of the previews to keep track of which window is which not which tab is which. If you ever find yourself with more than one window those previews do more to hinder your ability to find the tab you want then help. And if you only have one window they’re still too small to help you much anyway.
Single words in the omnibar are still queries
If you type a single word into the omnibar in IE9 it will first look on your intranet for a machine of that name and attempt to connect to it instead of issuing a query to your default search provider like every other browser. This is an especially annoying feature because not only does it do something unexpected it’s typically a lot slower to find and connect to a local intranet machine than a search provider, so your query ends up spinning for a long time then taking you to some unexpected server. Not cool.
If it isn’t a URL then it’s a query!