I don't know any.
But many LFOs accept a wide range of control voltages, so you could patch a +/-10v CV source in the form of a big knob or a fader into one and get the result you're looking for.
There are many such CV sources, and they're usually cheap. My favorite one is the Antumbra Fade. (It also doubles as an attenuverter.)
-- fredeke
Oh... This could be a really nice way to solve this single knob problem, Antumbra Fades are quite cool... THANKS!