Rachel writes: "Now running at the Horowhenua Libraries Trust [1] in New Zealand, is Koha [2], an open source, free library system written by Katipo Communications [3]. It is a true library system, not just an OPAC, that runs as a public website, a library intranet and issues and returns via a telnet interface." That download link still isn't working tho... [the correct link to download is here [4] (thanks Jeremy).]
Links:
[1] http://opac.library.org.nz
[2] http://www.koha.org/
[3] http://www.katipo.co.nz
[4] http://www.koha.org/download/