Free forum software/service with Facebook Connect and OAuth integration?

I’m trying to set up a web forum for a tiny nonprofit, but specifically, one that lets users choose to register and login via Facebook Connect or OAuth (e.g., “Sign in with your Google Account”).

There are some hosted services – such as Zoho Discussions and Tal.ki – but they’re a bit out of our price range. As a new organization, our web budget is currently extremely limited and we’re looking for a service (or software we can install on our own website) that’s ideally either free or very, very cheap (a few dollars per year).

Any ideas? We’re considering setting up BuddyPress with some authentication plugins, but that may be overkill. Are there simpler forums with this functionality, either built-in or plugins?

Thank you!

Are you wanting hosted forums, or will you be hosting it yourself? If the latter, you could try Simple Machines. It’s free, PHP-based, and there’s a mod available for Facebook connect.

Otherwise, if you eventually scrounge up $150, you can buy an Invision Power Board license and it supports Facebook Connect out of the box. (I use Invision for my forum, and I prefer it to vBulletin–although, both are nice.)

That mod doesn’t really work, unfortunately… it pulls some info from your Facebook account and prefills some forms like your username, but it still wants you to make a new SMF account. Kinda defeats the point