The professional networking site LinkedIn is built with community managed open source. 'At LinkedIn, we love open source,' we read in a recent blog. 'We’re committed to contributing to Hadoop and Pig and giving back to the open source community through projects like Azkaban and Voldemort. We are determined to provide the open source community with the complete and painless data cycle that we enjoy – to enable even casual  Hadoop users to analyze data from their application at scale, to mine it for value and store it easily and reliably so that it can drive use and close the data loop.'