Today's technique uses very basic pieces meaning you can build it yourselves, but the effect is pretty impressive and does well in capturing the qualities of a flowing waterfall.
Built by David Leest on Flickr, the overall effect is stunning but it can be broken down into 3 steps as shown in the picture. It relies on building sideways, utilising the plates thin profile so that various blues and white can convey a sense of flow of the waterfall.
Make sure to check out the full tutorial here as well as a bunch of other tutorials on the Brickbuilt website: http://www.brickbuilt.org/?p=7763