Website: Lots of general information about all aspects of the organization, including membership and the annual conference.
Listserv discussion groups: Several of these--including ATLANTIS, the very active general purpose list--are open to non-members, although you may be asked by the list administrator to explain your interest in participating. The lists also have a web interface, which you can use once you've created an account to browse or search the archives.
Job postings: The world of North American theological librarianship is a small one, so jobs don't come open all that often, but when they do, you're more likely to find them here than through ALA or ACRL.
I enjoyed meeting many of you at the recent ALA Midwinter meeting, and I hope the PRT group will continue to become more active.