I've been working on a C/C++ Source Code search website for over a year now, and just thought I'd let you all know that I put it live recently.
It allows you to search over 136 million lines of open source C/C++ source code.
It actually understands C/C++ syntax, thus giving you better results and code browsing capability.
I'm adding about 2 to 3 million new lines of code per day and always working to improve the speed of the site.
You can view the site at: http://csourcesearch.net/
I hope some folks find it useful