I used to use a folding metal pedal from MKS:
http://tinyurl.com/yr7ysd
They're available from QBP, so your local bike shop should be able to order them for you.
I wouldn't call them "very grippy," but they're better than the plastic folding pedals they replaced.
That being said, I gave up on folding pedals after breaking three sets (including these) in not too many miles. I switched to regular platforms and don't plan on going back.