ATE, A South African company, have an Mi-17 upgrade package:
http://www.ate-aerospace-group.com/s...background.swf
I have seen their Mi-24 Superhind upgrade flying at the Ysterplaat airshow. I don't know anything about any of it but it looked impressive (apparently it has composite rotors, a cannon slaved to the pilot's helmet, glass cockpit etc)
:
YouTube - Mi-24 Superhind at Ysterplaat Airshow, 2008
The promotional video is informative, although obviously biased:
YouTube - ATE Mi-24 Superhind - Promovideo
Another upgrade that seems interesting in a way:
Atlas Oryx - Wikipedia, the free encyclopedia