searchcode - A source code search engine
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
CRX Extractor - Get any Chrome Extension source code. Learn and hack!
Sourcegraph - Sourcegraph is a free, self-hosted code search and intelligence server that helps developers find, review, understand, and debug code. Use it with any Git code host for teams from 1 to 10,000+.
Binocs - Uptime Monitoring for the web in your command line
Krugle - Krugle is the complete enterprise solution for search targeted to the development organization.