koders.com is a really useful open source code search engine, which is able to find code snipplets within all the major open source code repositories on the Web. So if you are searching for e.g. Fibonacci, you are getting a list of code snipplets that are related to this word. You can aditionally filter for programming languages and available licences, which is quite helpful. The database that underlies Koders contains 3.3 billion lines of code and reflects the contents of the majority of world’s major open source repositories, with syntax-highlighting for over 30 programming languages. The search database is further enhanced with additional code and metadata from the Black Duck KnowledgeBase, the industry’s most complete database of open source and third-party code.