SO often you will find a list of social bookmarking sites in which top sites are the ones with PR but don't be blinded by the page rank top sites like delicious never come up in google search atleast for me I have bookmarked more then 1000 articles on various sites just to make sure the content on bookmarking sites remains unique I rewrote them still there are some sites which will never show up in google search despite best of your efforts and others will low PR will crawl up like instantly some examples being delicious.com ==> no matter how much you try it wont show ur article in google search buzz.yahoo.com ==> there are 10% chances that it will show ur article in google search reddit.com==> forget this site its useless BibSonomy ==> another useless site these sites usually dont get u in google search though if u have some exceptional articles which I usually dont only then u can expect urself to be gaining some traffic from them are there some more sites which users found useless please share
Those bookmarking you mention works fine with me the links are indexed in google you can try tumblr,blogspot,digg to boost your site presense