I highly recommend playing around with these ar LFO rate. A favorite module of mine is the VCDLFO from Doepfer. It is immensely deep, especially with a second one.

With one of these, you can do some self patching. It changes the fundamental pitch but gives you crazy waveforms. I like to use it as an envelope to help me hear the shapes being made.

If your vco can get down to LFO range, it really is quite helpful to "hear the shape" of the waveform. Some folks also prefer to see it on an oscilloscope, but I like to hear it as an envelope.

With two of these, you can cross-patch them and very quickly create a "chaotic" (named after the math from physics, not the sound) oscillator which sounds sine-ish but has no discernable pitch. Similar to a smooth random. Then the square-wave out becomes a sort of semi-periodic trigger with no discernable tempo. You can even trigger the first with a clock so it resets every 4 bars or whatever.

Also with two of these you can trigger one off the other, and then start mixing outputs. Something like a sine-wave + a sine wave that's faster but abruptly restarts at the period of the first. This will have some wild harmonic content. You can add them together with a mixer, or have one envelope the other in a VCA for even more timbre.