I'm interested in whether anyone has found big success through submitting to social networking sites such as Digg/StumbleUpon. They're so widely publicized, yet only sites that are already very large seem to perform well on them. Surely there major flaw is that they are a catch 22 - you won't get traffic from diggs as nobodies digging you, as you aren't getting enough traffic...
I've only ever gotten around 7-8 diggs (for 1 article) tops and perhaps 100 hits tops from StumbleUpon.