Google closed a lot of useful services to focus on Google+ and other core offerings. One of the best services that was recently shut down is Code Search, a search engine for open source code. If you go to google.com/codesearch, you'll see the following message:
"Sorry! Sadly, this service has been shut down. Much of Code Search's functionality is available at Google Code Hosting including search for Chromium. We're very sorry for the inconvenience."
Even though Google says that the service has been shut down, it hasn't. Just go to http://code.google.com/codesearch and you'll see the old homepage. All of the old features are still available and the results aren't restricted to Google Code Hosting projects.