There are few things I hate more than web sites that move when I don’t tell them to.
My new favorite thing is the Firefox Flashblock extension. It replaces all Flash content with a blank box with a play button in the middle, so you can view the content only if you wish to. Meaning no more Flash ads flying over the text you’re trying to read. (I don’t block ads in general, since I want the sites I visit to make money, just ones that interfere with my use of the pages I’m trying to read.)
Hat tip to Radagast. (The ScienceBlogs tornado ad he mentions was the trigger of an polite but extremely angry email I wrote to their webmaster. Haven’t heard back, but the ad is gone at least.)