It suppose to increase traffic as you share your content across the internet. I have been weary of this claim since it actually just infers this. I thought I would do a nice little test on a few sites just in case I am missing something.
Over the last month I ran the widget. here is my results
I sent just under 4000 clicks through the system. In return I got less then 2000. So basicaly they stole 2000 clicks. It was pretty close to 50%. If I received as much as I sent I would say it's a great widget but losing 50% is pretty huge loss.
That can add up to quite a bit of money. My ad revenue was dropping and I figured on those sites guess what the click on this widget was going up.
So beware of this widget if you have it. When it started it only recommended sites within my site. I also had all the sponsered listings turned off since they send the money to charity.