We are all advised to submit our Lenses to social sites such as Digg and StumbleUpon to help generate traffic. But bookmarking without getting involved in the social community is unlikely to generate a great deal of traffic. StumbleUpon in particular is unlikely to be of any benefit to you if it is not used properly. If you would like to use Stumble to generate a rush of traffic, have a look at my latest Lens: How To Drive A Traffic Rush From StumbleUpon, I am sure it will help.
On a different subject, the new look to Squidtop is very good. I like it much better than the old one and the navigation seems to have improved, too. Good work by the management!