Most interactions between cultures require overcoming a language barrier, which is why multilingual speakers play an important role in facilitating such interactions. In addition, certain languages (not necessarily the most spoken ones) are more likely than others to serve as intermediary languages. We present the Language Group Network, a new approach for studying global networks using data generated by tens of millions of speakers from all over the world: a billion tweets, Wikipedia edits in all languages, and translations of two million printed books. Our network spans over eighty languages, and can be used to identify the most connected languages and the potential paths through which information diffuses from one culture to another. Applications include promotion of cultural interactions, prediction of trends, and marketing.