So I don't forget it.

A cheesy generic tcp proxy I found cruising the webs built out of netcat, fifos, and tee:

$ mkfifo backpipe
$ sudo nc -l 80 0<backpipe | tee -a inflow | nc localhost 8080| tee -a outflow 1>backpipe

This way you can also look at inflow and outflow to see what the actual contents were of the transaction.