Frankly, animations in general. Okay, for Web-based video games, maybe I get it. If your website is not a video game, why am I watching visual elements zing around? If I walked up to a bank or a grocery store and then had to stop and patiently wait by the door while some animation involving the store's logo or bank played, how many customers would take that store seriously? Why are you doing it on your website? I don't want fade-ins, fade-outs, buttons that slide in from the side, anything like that.