Competitive Heatmap Analysis - Any website's heatmap data is at your fingertips
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
SendView - The best way to track your competitors' email marketing.
BuiltWith - Find out the technology behind websites
Monitor Backlinks - Easy Link Management - SEO Tool for automatically checking your backlinks.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.