OpenDNS is a great idea, well-executed. They took something basic and ubiquitous, DNS, and improved it by adding spell-checking and phishing protection (usability enhancements). They provide the service for free in exchange for monetizing typo search pages. The typo search pages are simple, fast, and generally useful. What I was looking for is usually the first result. There is no software to install, just two settings to change, and they provide a registration-free way to set preferences on their site. John Roberts is a friend from my CNET days and gave me a preview a few days before they launched, I've been using it full-time ever since and it has been invisible in all the right ways.