This may be completely not what you're looking for, but take a look at Cypress' PSOC devices. They have an interesting mix of analog and digital programmable blocks.
You can do digital control of analog circuits, PGA, digital pots, etc.
Just had a fun idea, you could use an LED to charge a rotating photoluminescent medium and then read out the intensity some rotation angle later, it be like a magnetic tape loop but have its own decay as well. Modulate the speed of rotation, the read angle and the intensity of the write.
I graduated before we got it releasable, and haven't had much time with my job to finish up the project. I don't have more time to add to this explanation, but if you want more info or implementation help, feel free to email me: alecdibble at gmail dot com.
Interestingly they use a switched-capacitor design, which means you can only input signals lower than the clock frequency used for switching the caps.
I had a look for continuous-time FPAAs but couldn't find any.
My goal is simply to make a guitar FX pedal with them, as they can alter gain, perform filtering such band-pass etc.
Potentially I could see it having lower latency than DSP, if anyone knows more about that, I'd be very curious.