Some simple effects based around changing the image based on luminosity thresholds.
I like the more subtle effects best, I think. I’ve always liked the effect of selectively desaturating an image, and desaturating based on luminosity seems to work well. What would be even cooler would be to be able to desaturate the image based on hue, so you could make an image monochrome, except for a particular colour.
Sorry about the photos of me. It’s not because I’m some kind of egomaniac. It’s more that I’m generally too lazy to use anything other than my laptop’s builtin iSight as an input when I’m developing qcFX.