On Monday a post on this blog was on the front page of Slashdot and then on Tuesday the same link made it to the front page of Digg. Since my blog has Google Analytics enabled this gives me an unprecedented opportunity to measure the number of visitors from each site for the same story.
Here are the referrer stats for the period:
So Slashdot brought in 45,473 unique visitors and Digg 13,009. That means the posting on Slashdot was worth 3.5 times as many visitors as Digg.
There's one big question which means that the Slashdot effect might be bigger than stated here. Monday was Labor Day in the US with a lot of people taking time off. Perhaps Slashdot's readership was lower on Monday than normal meaning that the Slashdot effect is more than 3.5 the Digg effect.