After/between request callback

Hi, I couldn't find an issue with this so here it goes.

I would like to run some code after the request has been flushed to the client but before the next request. Essentially be able to queue up some work per request without affecting the load time. An example is to defer some logging/profiling, or send an email.

Is this possible to do this already? Or is it possible to add? Thoughts and feedback more then welcome.