I followed this link to The DaVinci Code Quest on Google. It's an interesting concept - they have crafted a series of puzzles that you need to solve in the days leading up to the movie premiere of The DaVinci Code. I solved the first one and expected to have to go to a page where I would register etc but instead - Google did it for me. They knew my gmail user name, and presented me with a screen asking if I wanted to add the puzzle quest to my personalized home page. I said yes, and there it was - a nice little block on the side of my Google homepage showing my progress to date.
I was totally impressed with the whole thing. And scared shitless.
I'm giving Google so much access to my movements and habits. I'm using Gmail and while I know that they can't possibly have enough resources (much less the inclination) to truly monitor and read my email (among other things), just the very idea that they could, if they wanted to, scares the shit out of me.
But I'm playing my own little game - I tweaked the code on the link above. I'm just curious to see how closely they are monitoring from whence their traffic comes ... and if it ever finds its way back to me, some way, some how.