I found your article, because I'm one of the people who are very active on DIGG.This idea of marketing with a contest is very good, but not that way ( on digg ).Digg is a website where news & articles become popular if more people consider that they should be popular.The news or article should be news worthy to be on the from page, and receive the big traffic.This post is not for the first page in my opinion, and I'm not the only one who think this.Is just a a small contest.
Now I have an advice for you.If you want more readers, you should concentrate on providing value, quality and fun.This is the true way to get people on your website.The hard part is to be consistent and keep them on your website.
Anyway ... I've joined this contest because I want an Ipod Shuffle for a long long time, and maybe this is the change to win one.
P.S - English is not my natural language, so I might have some mistakes.