In my opinion, there's a "synth pedal" that's flying under the radar: DSI Evolver desktop synth.
It's actually a synth but it really offers a lot of processing options. I have one and read on the internet that it's quite the beast for experimental guitar processing. Yesterday, I decided to use it to process my bass.
Usable parameters: lowpass filter (curtis filter, switchable between 12 and 24 db), highpass filter, feedback loop, digital delay, noise, digital distortion, bitcrusher, envelope, 4 lfo's and a 4x16 sequencer...
I quite liked it. It'll take some programming to write "external bass patches" and some sounds are really harsh (especially feedback, bit crusher and distortion). I'm curious whether the low end will keep up in a mix when distorting the signal.
Still, I'm going to give it a shot to write some patches and see if I can produce decent enough patches to take it to the stage as some kind of warped multi-fx unit. To be continued
Anyone else using the evolver to mutilate their bass tone?