Preventing screen scraping

Following my recent posts on screen scraping, I've had various email discussions on the prevention of screen scraping. In other words how can sites prevent users or automated scripts taking their data, without punishing real users at the same time?

CAPTCHA's (Completely Automated Public Turing Test to Tell Computers and Humans Apart) are used to stop automated scripts pretending to be real people. Before anyone comments.. yes I am aware that CAPTCHAS can be broken/beaten, even ones by Google & Yahoo!

Rendering is a newer approach that is being used to defeat scripts/bots and is being used online e.g. by financial institutions, coupon and ticketing industries. By creating an image of the data a site can display the information which is easily readable by a user, but much harder by a machine....