A quick and easy way to create a thicker sounding synthesizer patch is to use two oscillators whose frequencies are slightly out of tune. With a minute amount of detuning, you can hear a bit of flange in the voice, as various frequencies are phased in and out through phase cancellation and phase reenforcement. A bit more detuning, and it can create a chorus like effect. Excessive amounts of detuning will cause the listener to hear two separate voices rather than a unified voice. This all depends greatly on the audio source(s), as different waveforms and samples will get different mileage out of this classic technique.
Download detuned_oscillators.csd here.