I love using Express 4's Router for rapid API development, but I hate having to link existing functions to the router.use() function by mapping req.body properties to the function parameters. So I wrote the following script, which will automatically map each property. Additionally, if you have parameters called req or res, it will reserve those words to pass the routers parameters directly.
Note that this implementation assumes any function being called will return a Q promise. It will also return a default status of 500 for any error thrown by the function, unless overridden.