Google Code Search:

I have many times searched for coding in the internet, often
people told me that there is search engine for searching codes.
I never knew about google code search then, until i came across
“Fast Track To Google” book .So now i know how to search for codes in the net,
Check it out for yourself
Google Code Search

Goole’s regular Googlebot crawler is being used to crawl
through archives(.tar,.zip,etc) and individual repositiories like CVS
and index all the files within.