There is a ton of portals out there. Most of them heavily modify phpbb so much that any mod you want to use you have to port over to it and pray someone has done that.
I perfer just adding the components to the forums to give it that portal feel. I use Smartor's EzPortal with album addon and attachment mod to add portal functionality, but yet leave my forums close to the original setup of the phpbb so that I can modify it with alot of these other great mods people release.
You can find both of those via a search on this site.