We discuss social networking software and give examples of its applicability for bringing together references for the study of cosmic deuterium. Our websi te at www.cosmicdeuterium.info provides links to all papers in the field, which is relevant to cosmology since all the Universe's deuterium was formed in the first 1000 seconds after the Big Bang . Understanding cosmic deuterium is one of the pillars of modem cosmology. Studies of deuterium are also imponant for understanding galactic chemical evolution, ast:rochemistry, interstellar processes, and planetary formation. By 2006, social networking software had advanced with popular sites like faeebook.com and MySpace .com; the Astrophysical Data System had even set up My ADS. Social tagging software sites like del.icio.us have made it easy to share sets of links to papers already available online. We have set up del.icio.us/deuterium to provide links to many of the papers on www.cosmicdeuterium.info. Links to a del.icio.us site are easily added, the prime advantage of such software. Use of keywords allows subsets to be displayed, though only papers already online can be linked without being separately scanned. The opportunity to expose knowledge and build an ecosystem of web pages that through its use by many people captures knowledge collaboratively is considerable. Setting up such a system marries one of the earliest stages of the Universe with the latest software technologies. The method of setting up a del. icio.us social-tagging site, which is so easy, is applicable to a wide range of educational purposes.