Reader aymat let us know about Superfake – a  free/nagware VST for Windows that emulates the famous Roland Supersaw:

Place it behind you synth in the audio chain or route any other signal thru it. When feeded with a saw wave, the output will sound like a Superwave. But every other signal will also do it. Superfake is more than a chorus. It delivers six detuned voices, which can be spread in the stereo field. The amount of detuning can be adjusted for a wide range of applications.

Note: While Superfake is free, it displayes a ‘nagware’ screen at startup. If you like it, you can get the version without nagscreen for 9 Euro.