google it...
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
tanh(y(y^4+5x^4-10(x^2)(y^2))/(x^2+y^2)^4)
Holy fish
Pretty!
best bit about this is that it is a feature, not an easter egg (although that does probably mean some poor bastards site just became pointless). Play around with the numbers and it's all done live. Probably quite useful if you know what the hell any of it means!
25 years ago my school got its first computers - BBC Micro Model Bs. The first thing I did on one after I learned to code was plot mathematical functions across the two axis of an isometric wireframe grid (waiting about two minutes for each one), capture the screen in an array and replot with a slightly altered range of values. After building up a dozen frames, I cycled through them in a looped animation. It didn't look a million miles away from this.
The PC I'm typing this on is more powerful than a Cray 2 (and a lot of yours will be too) but I'd struggle to repeat the trick on this. Now I have no need to; I'll just use Google!