Click the Build Profile tab, and BuiltWith serves up a list of resources for creating a similar site. Some resources are online, others are books. Here's a snippet from the Build Profile for OptimWise.com:
The BuiltWith Internet Technology Usage Statistics area of the site shows you trends and popularity stats about many web technologies. A few interesting categories: ads, analytics, blog, CDN, CMS, feeds, framework, media, server, and software.
Here's a graph from the blog page. As you can see, OptimWise.com is in good company by running on WordPress:
I've stuck to the basic information they provide for free, but there are paid areas of the site as well. One is the Website Optimizer. Based on its analysis of the website, BuiltWith will recommend ways to improve the technology and SEO of the site.
Knowledge is power, and it can be used for good or evil. You can use the site profile for research or for planning your own site, but you could also determine how to attack a website by exploiting vulnerabilities in the technologies that run the site. As with any info you find online, you choose how to use it.
Please share your thoughts in comments! As always, contact OptimWise for more information or assistance!