Inserting output from a program into a buffer

[Tim Johnson]

emacs 22.3.1 on slack 13.0/32-bit

Consider the following text:

[[10:00 11:27][14:43 14:57]] ;; ^output here

Given that I have selected:
"[[10:00 11:27][14:43 14:57]]" 
as a region, I would like to send that region to an external application
and insert the output as indicated.

I've recently started using emacs again after several years, and have in
the past written quite a few elisp functions and keybindings for my own
use. The external application has already been written, I've used it
with vim and "r !<shell command>" for years.

References to relevant and related elisp functions and scripts would
probably be sufficient, however, if someone has done this already - why
re-invent the wheel?

TIA
-- 
Tim 
tim@johnsons-web.com
http://www.akwebsoft.com