So I was looking for the "Contingency design hall of shame" that 37signals had running at the URL http://www.37signals.com/dnf/ some time ago.
But that link had died - and instead I didn't get a well designed error page like you might expect, given the content of the site that used to be there, but instead an advertisement for a book. The table of contents was listed, and the book's 7th chapter was described like this
7. Get Out of the Way
Eliminate obstacles to conversion (e.g. unnecessary ads, registration, navigation, etc.).
Sadly the item of value to me on the 37signals was gone.