Google earth: It's an excellent 3D tool... FREE! To view a demo
The main page.
You need a modern computer and a high bandwidth connection.
In the USA all charts have been encoded into the standard ENC format. ENC charts of the entire country are available from the NOAA web site...FREE. Raster charts are also free.
Now it's possible to have these charts overlay into google earth.
is the tutorial.
ENC charts is the world standard but not all countries have finished encoding, and most countries charge for it. Still it might be worth checking out from whatever country you reside in.