There are good uses of AJAX and bad uses. The Snap Preview Anywhere widget is what I would consider a bad use. I cringe every time I go to TechCrunch now and actually wan’t to visit one of the sites they mention. It’s distracting and unexpected (I hover over a link wanting to click on it and all of a sudden this damn window pops up). Even if I wanted a preview of the site, the thumbnail isn’t big enough to provide anything of value other than a cursory look at the page’s design. I think it’s on its way to becoming the blink tag of the blog world.
Please, I beg all site owners, do not use this thing.