In writing about the launch of Google Custom Search Engine, I neglected to mention a couple of other companies doing similar things. The first one omitted from my post was consumer-focused customized search engine Optevi. Optevi allows users to choose from or create "bundles" of sites that influence search results.
The selections that users make affect the inclusion or prioritization of the websites presented in results. Those who may be initially confused by the interface can take the tour and hear founder Daniel Abrams explain how it works.
The second company I neglected to mention was Microsoft, which also offers the ability to build a customized search engine.