Pass data to a nested Async AJAX call

This is not specific to SharePoint iteself, but I find myself using the SP Rest services more and more.

This stumped me for many hours. Lets say you have two async ajax calls. Further, lets say you need the results from the first call in the second. Sounds easy, but there is no way to jam a parameter in the .done() function and everything goes "out of scope" when you go from the first call to the second one's .done().

Solution? embed the data in the HTTP call itself!