Yes, there are several android navigation apps:
Also check the android market for navionics. It's not cheap but it's there.
The limiting factor you're going to have is integration with the rest of the on-board electronics. e.g. the GPS (although the android platform includes an inbuilt GPS, onboard ones are usually more accurate), wind/depth/speed instruments, etc. Very few android devices even have a USB port for data input and none have a serial port with which you could bring in NMEA data. You're not going to get the same sort of functionality with an android tablet or phone as you will with a laptop or chartplotter. It's OK for checking rough location up in the cockpit, though, especially with the free NOAA charts if you are cruising in an area covered by those.