I'm proud to say that I have a Droid phone and not one of those Iphones, although my has an Iphone I like the droids better. Anyway I found a Navionics App for my phone. It costs $9.99 but that's better than paying $150 or more. This way if I'm not on my Yak I can still mark areas for future trips, and plan trips and such. I highly recommend it.
http://www.navionics.com/NavionicsMobile.asp