Found this illusion site, so weird.
http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html
Ebaums also has a bunch of good illusions. illusion 1 and 3 are wrong. if you look close on 1 square A is spiked with darker piments and B has occasional lighter ones. on 3 even with the blind i can see a color difference.
Well, apparently your eyes are better than mine, Brain. 
The illusions work on me.
I have seen the first two before, but not that last one.
do you have your monitor set for 24 bit or true color mode?
you can screen grab those web pages by hitting the [print screen] button on your keyboard, then [ctrl][v] paste them into paint
and capture the color from one area and draw it into the other - or cut and paste parts out of the pictures and put them side by side
the colors are identical.
yes the colors are but their is a spray of pixels that aren’t!
the first one does have some variances in exact color because the image appears compressed and it caused some slight changes in color, however there is the same amount of the same color pixels in each square, all arranged in about the same pattern. I tested this in photoshop and was impressed how similar they were. I also made this quick gif that overlays square A and B to show how similar they are in color
http://img35.imageshack.us/img35/2977/proof1wl.gif
on 3rd image, I am sure that the objects are the same color, but because it is a 3d rendering, the shadows make it nearly impossible to check in photoshop. I took 6 samples of the cross in the middle for each cross, but I never managed to get the exact same color, but the colors were very similar, enough to prove the point the author was trying to make in the website.
just my $.02
yeah I’m just a perfectionist thats why i can pick out individual pixels!