I have never used Stumble upon but I have many links to my site on it. Stumble brings me roughly 500 uniques per week. I was interested in purchasing some credits from StumbleUdon but I am not 100% what stumbles actually mean. Basically StumbleUdon tells me I can buy credits, $13 usd for 100 and each credit gives me on Stumble. What the heck is a Stumble? Is that a visitor to my site? or is it a 'I Like It!' thumbs up on the Stumble bar? Or is a review on Stumble? I cannot find out exactly what a Stumble is. Any help guys? I was hoping to shoot my uniques from Stumble up to 1k per week if possible.