cj, if the site that you have submitted are brought up to the frontpage of the digg sites, they can bring tons of traffic ranging from 40,000 hits or more depending on the story. less famous digg-alike sites gives a little traffic of course.
ive had a "news article" that has got over 100 hits from digg with only 2 diggs.. same with the other ones its worth submitting something even if you know its shit and wont get dugg
I've also seen a decent traffic bump from using digg. My articles never got a lot of diggs, but it was better than zero traffic.
Here is the list I have of similar sites: (1) http://www.digg.com (2) http://www.fark.com (3) http://www.aworldofhelp.com (4) http://www.i-am-bored.com (5) http://www.isnare.com (6) http://www.slashdot.org (7) http://www.boingboing.com (8) http://www.hypersuper.net (9) http://www.shoutwire.com (10) http://www.monkeyfilter.com (11) http://www.popdex.com (12) http://www.reddit.com (13) http://www.blogslip.com (14) http://www.pligg.com (15) http://www.viralcow.com Thanks.
Plus if you get the front page other sites like popurls.com will link to you and you can get a whole shit load of traffic that will kill your server.