Apigee provides a way to expose a custom API to users of third-party software.
I have been testing some of it by creating a console to go for the Foods grammar, embedded below:
In order to get such a console, the API has to be described using WADL, the Web Application Description Language, attached my current simple version in case you want to expose your application grammar.
BTW, the youtube channel of Apigee is very informative, http://www.youtube.com/user/apigee.