If anyone is looking for an inexpensive case to use an iPad onboard, I just bought one from Trendy Digital.
I forget where I saw the article but there was a comparison of several options up to triple digit prices and this got pretty good marks.
Its essentially a ziplock baggie, but it has some padding to help protect the iPad from bumps. With two zip lock seals and a fold over snap/velcro closure it should do a fine job of keeping the iPad dry. If you need to use the headset jack there are other options but since I don't need access to the jack for onboard use its not a big deal. I would like a solution that allowed the unit access to ships power though.
I was intially worried that the touch screen would be unresponsive through the plastic, especially since I already have an anti-glare cover on the unit itself. In use, this has not proven to be a problem, and the unit works just like the cover wasn't there.
I think its a pretty good investment to protect your iPad for use in the cockpit of a boat.
So far for app's I've just be using iReggata and Safari for access to weather sites. I may add a navigation app for a couple of distance races we have planned.