So, this is "let us track all your browsing activity" with a reward system and marketing that tries to leverage the trendiness of alternative currency, right?
PIXDO is not selling/renting any private information - just to put this off the table.
It's about content discovery and fixing the broken bounce rate of the internet.
You might just as swell say that reddit/hackernews/stumbleupon/pocket are tracking you by voting up certain posts and all their features are mere "marketing". On PIXDO you 'vote up' by visiting for 24 seconds that is all.
The main difference is that PIXDO give a full experience. It's not a utility, it's a seamless part of your browsing.
You can contact me directly at info@pix.do for more information, ask anything you'd like.