How about getting 10% more clicks to your Order Now page by changing button colors? Or 135% higher clickthrough on your landing page by using giant buttons? Test your design intuition at Anne Holland’s Which Test Won. They host real world A/B tests for a number of landing pages, homepages, lead generation pages, etc. It’s fun to test how your intuition correlates with the measured results. I ended up quite far from 100% intuition success rate…

Jeremy Liew of the Lightspeed Venture Partners wrote a good post about WhichTestWon.com (this is how I found out about the site). He has also a bunch of other great A/B testing related articles worth reading.

Google’s Website Optimizer is good tool to get started with A/B testing.