@Radiance: are you still looking for a tutorial on interiors with portals etc? I'd like to help out if I can.
Interiors are where I'm heading anyway. Trying to recreate "notsosimple" at the moment. If I feel my way through by asking questions on the forum (along the lines of my recent "dark glass" thread) then I would be pleased to write it up as I go.
It would help me (interiors are where I'd like to go next with my learning) and hopefully help you.