Folksonomies are systems of collaborative end-user metadata of digital assets. This paper explores how folksonomies could be used in public library catalogues to enable end users to (1) organize personal information spaces, (2) supplement existing controlled vocabularies, and (3) create online communities of interest. The benefits and shortcomings of folksonomies are discussed, as well as customizable features in existing library catalogue systems. A research agenda for the study of folksonomies is presented that focuses on a quantitative and qualitative analysis of folksonomies, as well the study of end users' metatagging behaviours. doi:10.1300/J123v51n02_06