The ability to cache the response of a HTTP POST request is very niche, and most of what you'll find online will tell you that you shouldn't be doing it. However if you have no choice then I can offer a possible solution as well as give you the software to avoid.
After re-installing RVM on my development machine I then found I could no longer interact with HTTPS services. This is how I fixed it.
After seeing some web based Roshan death timers I decided to make my own, but instead of just having the standard features, I added Ventrilo PTT binding support.
I have an unhealthy obsession with statistics, graphs and the like. One of the games I like to play, League of Legends, has a community run statistics site called LoLBase, but they are highly dependant on people sending in their game logs to generate the data.