Andy Beaumont explains why he created the awesome Tab Closed; Didn't Read Tumblr:
“This kind of belief in numbers is exactly what got us into this mess. [...] Analytics will tell you that you got more “conversions”. Analytics will show you rising graphs and bigger numbers. You will show these to your boss or your client. They will falsely conclude that people love these modal overlays.
But they don’t. Nobody likes them. Conversions are not people.”
I couldn't agree more. The modal overlay advertisement is currently one of the most user-hostile behaviors on the web, often appearing and requiring dismissal before the user even has a chance to check out the content they clicked through for. Who the hell would willingly sign up for your lame marketing newsletter before they even know what you're about?
Almost nothing will make me leave a site faster than these ads do, and I'm not likely to ever return. How's that for your analytics?