Krugle - Krugle is the complete enterprise solution for search targeted to the development organization.
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+.
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
searchcode - A source code search engine
Snip2Code.com - Snip2Code is a free service that lets users search, share and collect code snippets, the basic...
Text Sherlock - Provides a fast, easy to install and use search engine for text but, mostly for source code.