I was trying to figure out a quick way to emulate the GIMP script "Vintage Look"
http://registry.gimp.org/node/1348
I used the bleach bypass as a starting point then emulated the Yellow/Magenta/Cyan layers with Sadman's Texa. Using Texa you can also adjust the tones of the 3 variables. I'll probably figure out a more elegant way of doing this soon but thought I'd share.
Example :
