Do you try stumbleupon for generate traffic. I got lots of traffic from SU. For get traffic on SU website must have attractive look and should me one active member. I have make one post on my blog how to drive traffic on website.
Agreed... it can drive lots of traffic if used properly. Digg's traffic effect is well known, as is Slashdot's, and even Reddit, Furl, Shadows and StumbleUpon can send several thousand visitors.
Oh..!! Stumble upon is a huge social bookmarking site and thus it crawls on a daily and regular periodic basis. If you stumbles here.. your link will be definitely crawled and thus its really better to get your link here..!!
Stumbleupon really contribute to the site by generating good traffic. Try other social bookmarks like Delicious, Addthis, Social Marker, etc to get more traffic