I don't use a "tremolo" pedal per se, but I've learned that there isn't much difference between the circuits of a harmonic tremolo, and a uni-vibe. So, especially for synthy madness, I've learned that the uni-vibe is a little bit of a secret weapon. Not sure how I'd use trem with a more "traditional"/clean sound, but for experimental things, it's pretty awesome.
This is a little sound clip I did up a few days back, and the uni-vibe features in all the tones, but especially the first two: