We have a great app on the iPhone that we use when we're on the boat called Navionics. We don't have a gps or chart plotter on the boat but this app replaces the need for all that. Dont get me wrong, Jay would love to get an all in one gps, fish finder, chart plotter for the boat. But in the meantime, this app works great. It gives us our speed, heading, and gps location on the chart so we can see the depth. Only $20, not too bad. So if you have an iPhone 3GS or 4 and have a need for nav chart info, check out this app.