On the detachable side: I don't think such a creature exists, and I've looked a bit. I did read one post on a forum somewhere, where someone showed how they modded a set of MKS EZY quick-release pedals to do this, but I think the project was really for the home machinist/tinkerer type.
FYI, currently I'm using the Campus Pedals from Performance. I know they're not folding, but seems to work for me.
DO NOT, I REPEAT, DO NOT BUY THESE!!! I tried the exact same product on my SPD's and they were near impossible to take off again. They are all resin, including the section of the pedal that clips in. Even with my SPD pedals set at the most sensitive setting - the one that my shoe would come out of by just breathing funny - it was near impossible to get the pedal adapters out. After a few experiments, I finally had to cut one of them off the pedals. Let me tell you that I am a 6' 230lbs+ man that weight trains regularly, so if I can't budge them, they aren't coming off. The other adapter posted by CrimsonEclipse is a much better design because it allows you to use actual SPD clips. If you decide on adapters, I would go with that other product. In addition, the Nashbar product would not work with MKS pedals because MKS pedals use a clip that is similar, but not the same as an SPD.
that other product. In addition, the Nashbar product would not work with MKS pedals because MKS pedals use a clip that is similar, but not the same as an SPD.
I had a set of these for the look style pedals (Performance sold them), and it also was hard to get them out. I used a screw driver shaft to pry open the tensioner while I removed the pedal. Perhaps same mechanical advantage needs take place for removing SPD style.