I manage have either my blog or Sampa appear at same pretty impressive sites.
Last year, a post that I've made about improving the speed of web pages end up at #1 in Digg's Homepage. That drove about 10,000 unique visitors to my website.
In August, Sampa was feature on CNET News.com on the #1 spot on their Homepage (you know, where the 3 images appear, we were the first one). That drove about 7,000 unique visitors to Sampa.com.
Three days after the News.com article, LifeHacker wrote about us as well, generating about 3,500 unique visitors to Sampa.com.
And yesterday, my "mystery" blog entry was featured on Boing Boing and that generated about 1,400 unique visitors. Boing Boing is the #2 most popular blog according to Technorati.
Boing Boing probably has more than 100,000 readers, however, since they publish so much on a daily basis, no post survives more than a few minutes on their Homepage.
The Digg post was very controversial (amazing how a technical post can be controversial), and that is why it generated so much traffic. A lot of bloggers wrote about it, helping to drive even more traffic.
CNET News.com on the other hand was the most effective for our Startup. It generated an immediate huge traffic to Sampa.com, and had many ripple effects on other sites and blogs like LifeHacker, ZDNet, ZDNet Japan, etc.