I don't really know if such a thing exists. Every so often I want to ride my road bike with Look cleated pedals but I don't want to wear my road shoes -- like if I'm towing my kid in a trailer to the park. I can actually ride my Look pedals in street shoes, but it's uncomfortable and they're too narrow to generate much power. Does anyone make something like a platform adapter that clips into the pedal to provide a temporary pedaling surface?

OK, found what I was looking for at Performance, if anyone else is interested: https://www.performancebike.com/shop/profile.cfm?sku=346

or amoeba also make such a thing

I've tried the Performance adpaters; they're a pain in the a$$. It's easy to click them into the Look pedal but getting them out is a real problem. It takes me less time to remove the Looks and install my flat touring pedals when wearing .regular shoes. My 2 cents.

Those are scary looking. They look like you could use them to trap small animals when you're not riding.

I bought those winwood instep things and found them pretty much worthless. At the maximum adjustment they are too small for my feet (size 10) so I have to ride with only my toes on the pedal. They are poorly balanced so it is much harder to flip them up than regular clips. They come off easily when riding, with difficulty when you want to change them out. I find it more practical just to stand on my clipless pedals with street shoes, or to switch pedals.

I'm considering buying a set of the Shimano platform pedals with the "pop-up" SPD clip, but I have no direct experience with them.

Gee, I already ordered the Instep thingies; I hope they're not a complete failure. I'll only be using them for riding within the neighborhood, 2-3 miles tops, so they don't need to be super-effective.

Well, the Instep adapters came last night. Basically they are about the same size as the Look cleat, with a plastic toe clip coming off the front. They have multiple sets of bolt holes so you can adjust the distance from the front of the toe clip to the cleat. I set mine on the deepest setting and snapped them in, then went for a short ride with my Teva's. I think these will work out OK for what I need, but I sure wouldn't use them for any ride longer than a few miles. The pedaling surface is still too small, but the toe clip adds a little bit of stability. I didn't have any trouble unsnapping them from the pedals, just grabbed the toe clip and gave them a twist. (My pedals are set with fairly low tension).

Finally a poster that actually posts their findings instead of saying I got it and deletes their post.