Support Ticket Feed as on this site…How to?

Is there a plugin that will feed the Support Ticket system into a page as on or is that a custom solution?

I have considered BuddyPress but believe I read somewhere that BuddyPress does not do well on a multisite install but a subdomian.

If I choose BuddyPress, could I still make it a single-sign-on from a subdomain?

In short I’m looking for the best way to have a support ticket system and forum.

Thanks for your help.