This paper emerges out of my recent research on Maghrebi music, especially Algerian rai. I have discovered all sorts of previously impossible-to-find music, plus photographs of musicians and albums, stories about artists and recordings, and transcribed and translated lyrics, posted variously on music blogs, Youtube, podcasts, and SoundCloud. All this new data has been invaluable in my research on rai's history in the sixties and seventies. But it would be a mistake to treat this material as simply raw data. For one, information, interpretations, and meanings of posts are frequently discussed and debated in comments, sometimes heatedly. Comments are continually being added. Youtube users sometimes post a "rare" recording as a "response" to a previously-posted "rare" recording. The "data," then, is constantly evolving and never unquestioned by users. In addition, while posters are motivated by the love of old music or the wish to fill in gaps in knowledge, other interests and desires are also at play. Sometimes posts promote musical artists and genres forgotten or suppressed by official, canonizing national cultural histories. Others boost regions or cities whose role in the development of a genre is marginalized (for rai, Aïn Témouchent and Sidi Bel-Abbès). Some music posts advance a multi-cultural vision of Algeria, in opposition to official Muslim-Arab regime narratives, reviving, for instance, Algerian Jews' contributions to national music culture before 1962. The role of Maghrebi artists who recorded and performed in Europe, as well as Maghrebi-focused record labels in France and especially Marseille, are also remembered and advertised. Other posts are occasions to criticize the Algerian regime in its "heroic" liberationist phase, for instance through the recordings of ouahrani artist Ahmed Saber, frequently in trouble with the government between 1962 and 1971 for his satirical lyrics. This archive also poses novel opportunities and responsibilities for the researcher. It affords new ways to publish (via blog or posts of one's own "rare" music), the potential for reaching larger and/or much different audiences and receiving highly specialized feedback than through academic publishing, and the possibility to participate in collective projects. Yet there are also concerns about the permanence and quality of this archive -- blogs are suddenly taken down, copyright complaints lead to the deletion of recordings, and the longevity of hosting institutions is by no means guaranteed. All these issues call for critical attention on the part of researchers who take advantage of these emergent social media resources.