My favourite for water is pucker.cal. I am not sure where it came from but here it is:

{This puckered texture is used to provide a bumpy look.
A1 is the degree of puckeredness puck_dx, puck_dy, puck_dz are the perturbation variables in the x, y and z directions.}

puck_dx = A1 * noise3a(Px, Py, Pz);
puck_dy = A1 * noise3b(Px, Py, Pz);
puck_dz = A1 * noise3c(Px, Py, Pz);