I have not seen iPod/iPhone cases from Otterbox. I've seen some protective cases from Marware. They looked very similar to the Impact Case from Otterbox. I found that they were on the heavy side as rubber they were made of was thick/compact. It might be a problem or not.
Edit: from the OtterBox spec sheet, the Impact case weight is around 17g or 0.6 oz and it's not made out of rubber but silicon
Mike,
I've been using an Otterbox since I dropped my first Iphone and had it replaced. It was actually an Apple care tech who recommended it !! Since then, no fewer than 5 friends have bought one after seeing it. It does provide a very good shock proof case which also covers the screen......and I have proven it, believe me !! It fits like a clamshell around the phone, then you stretch rubber over that. They DO make a waterproof version, but have no experience with it. I highly recommend it. They were running a buy one get one sale which I took advantage of for gifts.
Jim