This is pretty awesome. Plug these equations into your search bar.
Google originally shared this post:
sqrt(x*x+y*y)+3*cos(sqrt(x*x+y*y))+5 from -20 to 20
sin(5.5x)*cos(5*y)+x*x+1 x is from -1 to 1, y is from -1 to 1, z is from 0.1 to 2.8