http://poseworks.8m.com/tu-wave.html is the best one available. I'm working on a tutorial now. if you make anything that is cool please please let me know. it would love to include it in my tutorial. to see something i've made go to my tutorial site and download wave example I made. There are also some wonderful links here on R'Osity do a search for wave. About a month ago Grey Mare made a post of a waving flag. Also the 3D Worlds stuff. Available in the store. they have an ocean and a prond prop that goes with their skies and terrains. It uses wave deformers to allow you to have animated water.