Stumble Upon is the biggest driver of traffic to blogs and websites on the net, far surpassing facebook.
It is an important tool for traffic generation to your blog. A lot of people complain that it does not bring loyal readers to your blog because most people are quickly stumbling through giving random thumbs up.
The more I use it the more I see this to not be necessarily true. And if you use it in this way, Stumble Upon won’t reward you.
Stumble Upon is where I do most of my online reading, it is where I most discover new blogs, blogs that I have become loyal readers of and who I have now written guest posts for, which have driven me more traffic.
Via Martin Gysler