This is something I've done part time, at the beginning it was to satisfy my own need, and mainly for fun.
URL: http://www.xnapi.com/
I've been meaning to ask the YC community if this is something that you'd want to use. If you want, you can try the small demo with Gmap API I put together. Basically it is a website that would help you use web APIs without coding knowledge. Even if you know how to code, it could save you time reading documentation and learning the API yourself.
I know this is a hackers community and you might well feel that you can just work with APIs yourself. I'm asking for ideas on how this can be further developed. Any feedback would be greatly appreciated, thanks :)
Maybe just get rid of "The web today is full of useful...
...with XNAPI."
and go straight to the TRY IT NOW button.
I'd love to see more examples.