Tunefish

Tunefish is a tiny virtual analogue synth that was originally developed for the 64k intros of the demo group Brain Control.

The synth itself is developed to fit into 10kb of compressed machine code, but they have decided to release the larger VSTi version of it for free to the public. The synth is an ongoing project under active development and feedback is very welcome.

It uses a spline based oscillator that can by configured very dynamically. Additionally to that, it contains an additive synth.
Additionally to normal sine, sawtooth, triangle and pulse waveforms, it can do anything that is possible with 6 points and step/linear/spline interpolation.
The Noise generator can produce any frequency of noise with any bandwidth.
Lowpass, Highpass, Bandpass and Notch filters are available.
4 ADSRs and 4 LFOs that can be linked to pretty much any important knob using a modulation matrix.
Supported effects are Flanger, Chorus, Distortion, Delay, Reverb, EQ and Formant.
The effects stack allows for any permutation of up to 10 effects.