You can use the OSX open program to create a simple and effective ~/.mailcap file to view HTTP bodies:
application/*; /usr/bin/open -Wn %s audio/*; /usr/bin/open -Wn %s image/*; /usr/bin/open -Wn %s video/*; /usr/bin/open -Wn %s
There's a todo file at the top of the source tree that outlines a variety of tasks, from simple to complex. If you don't have your own itch, feel free to scratch one of those!
© mitmproxy project, 2012