I bet at least 90% of 37signals click are "above the fold". If I was a betting man I'd take that bet. From looking at the stats on sites with a similar layou

I bet at least 90% of 37signals click are "above the fold". If I was a betting man I'd take that bet. From looking at the stats on sites with a similar layout I'd guesstimate that only about 30/40% click above the fold - and some portion of those users will have scrolled and read the other content before doing so.