My company has a customer company called Klikcard, which business idea is to sell gift vouchers of different kind of vendors through their website. For me, as I'm a lazy ass gift shopper, this has been a very excellent idea from the start. We have used Google Analytics for counting conversions and analyzing the web-sales process.
When I was in my summer vacation, my client studied the process very carefully. Earlier we found out that too many people abandoned the shopping cart in the first stage. We made a small change and just for one word. But the word seemed to be very important. In the shopping cart we changed "preview" to "sample" (in Finnish language the difference is not so obvious) and it worked out pretty well.
And of course, we checked out the numbers. During the two first weeks of July, approximately 25 % of visitors went forward in the sales process. After the change, during the last two weeks of July, about 38 % of visitors kept on going. Just one small change to one single word and we improved visitor behavor closer to conversion up to 49 %!