One of my best investments has been a $10 Navionics app for the iPhone. It should be available for others as well. I see it is available for iPad and Andriod as well.
http://www.navionics.com/NavionicsMobile.asp
I have a Garmin 440S with the 3D chip, but the screen and view of the Navionics app is so much better, I find myself using it more and more. Much better visual than the Garmin, more like seeing your boat on a paper chart.