Used it for my Master's thesis in 2009 (with LaTeX via xelatex), for my wife's Master thesis in 2011 (idem), and now we use it to keep a catalogue of the books we own (just a small home library of about a thousand titles). For the latter Zotero is also great because of its integration with on-line library catalogues. You just type in the ISBN number in the magic box, and the book's metadata is there — in any language!¹ Mostly just a few tweaks to the data are necessary, but it works rather well.

1: Tested with English, Dutch, German, and Japanese novels.