My equipment includes helmet, hinged knee braces (a holdover from skiing), and specifically for boarding I've added wrist protection and the afore mentioned Burton RED hip pads (last season's grey mesh model).
I *think* I cracked my tailbone last season while learning to snowboard -- it's only now getting comfortable to put pressure on -- so I purchased the hip pads in response. The Burton RED weren't my first choice; based on reviews, I'd prefer to own the Dainese but I couldn't find them locally. The RED tailbone protector is relatively small, but it does offer some modicum of protection. I've left the removeable butt pads in place, but have 86'ed the smaller thigh and groin pads.
This season's surfer-style RED shorts are certainly nicer looking, but I wonder if they are too warm to wear under insulated ski pants with (presumably) underware or (my choice) bike shorts as a "sanitation layer."
Wrist guards are a nuisance, but I feel naked without them. Now that I'm attempting some mogul runs and beginning to fall hard once again, there have been a few instances where I'm happy to be wearing them.
I don't know that the knee braces do anything for me on the board, but my knees are weak and lame and there have been instances where, literally, I could barely walk after a day of skiing without them. They do, however, offer a minimal amount of protection when I kneel down in the snow -- whether intentional or not. So I'll stick with them, just to be safe.
With the exception of the wrist guards, none of this stuff is burdomsome to me, other than when getting suited up. ****, I usually put my ski pants on at home before my three hour drive to the Tahoe area, which means an extra three hours wearing knee braces and (if I'm planning on boarding) sitting on butt pads the whole way. Whoo-hoo! snow, here I come.