Not just e-commerce sites but just about any website who's webmaster's goal is conversion of any sort can make use of Google Website Optimizer.

Conversion Rate Experts has listed 101 ways to optimize a site using this tool. Here are 10 of them:

1. Multi-variate tests
2. Time-split tests
3. A/B split tests
4. Google adwords
5. Live Chat - Many visitors are now getting more giddy with sites having this feature and what cooler way to get feedback but through live chatting?
6. Web analytics
7. Usability tests
8. Eyetracking
9. Poorman's eyetracking
10. Clickmapping.