Thanks to html5 canvas API now we are able to modify every image pixel by pixel!
I was thinking to make something useful and mostly crossbrowser with this and I had a great idea reading this post http://spyrestudios.com/html5-canvas-image-effects-black-white.
In that time I was working for a customer that just needed a portfolio web site using image thumbs that become black and white on mouseover and so I started making jQuery.BlackAndWhite.
This plug in is completely crossbrowser because I followed a progressive enhancement process forking my code checking if the browser running the script could support Html5 canvas.
It works on every modern browser, smart phones and also on IE7 +.