This blog is not mine but it does contain a LOT of digg like sites and other social/bookmark networks. Just find a few that relate to your website and start submitting. Worked a treat for 2 of my niche sites.
Not all of them, but only seldom of them can really bring you some traffic. I think 10 are enough. And I'm trying to see which ones are best for my site.
i think there is a post in the "link development" also had a great list of social bookmarking sites and its PR.I cant find it though.
http://ekstreme.com/socializer/?url=http://www.yahoo.com/&title=Yahoo! i think this list contain the more popular, if you choose your tag wisely, you could get more traffic that del.icio.us. with smaller site I 've got more traffic from bibsonomy.org than del.icio.us because i own a very good tag there
Although that site has some good content (from what little I managed to see) the owner needs to get rid of some of the nasty scripts he has running on it. The site chokes up my browser to the point where i can't even scroll down the page.
I don't know if you had this in mind, but here is another list of social bookmarking sites: http://forums.digitalpoint.com/showthread.php?t=187626&highlight=bookmarking