Ha, I've just noticed that I've got "excellent" karma over at Slashdot. I'm not arsed about the "my karma is bigger than yours" subculture, but it does mean that everything I post will start off with a score of 2 - probably bypassing a large portion of people's score filters.
That also means that I have a bigger chance of getting comments noticed and rated to 5. And that means that anything I put in my sig is going to get a traffic boost because it's got high-visibility on one of the largest tech sites on the Internet.
In other words, I have a good advertising route :)