- Autoplaying music or video. I tend to have lots of tabs open, and it's very annoying if you can't tell which tab the noise is coming from.
- Flashing/scrolling text, especially if it's an advert.
- Pop-ups, especially ones that are
- Advertising;
- Excessively needy - "sign up to my newsletter! Go on, PLEASE!", and/or
- Have the close button in an unusual place or an unusual colour
Seriously, if you're GOING to have needy pop-ups, it should have a HUGE red "bugger off" in the top right hand corner...
- Articles spread across multiple pages. The New Yorker is a particular offendor in this regard.
This list is not exhaustive. I bet you lot can think lots of stuff to add to it, can't you? Any really good ones I shall edit in and credit you.