I think not so important how many people are thinking. Mainly such sites are used for traffic, but if your service is specific, for example, company formation how many customeres visit your site and what much important is, buy your service. I am sure 0.1%. Indeed, social-marking sites are good for general or broad topics and useless for specific topics, where sites are looking for targeted visitors
It depends on your site's demographic. If most of your potential buyers aren't tech savvy, social networking sites may not do much for you, since most of the buyers will look for you on Google, not del.icio.us or stumleupon. The link juice from minor players might be worth something but they have second-tier value since the links aren't editorial.
Yah, but backlinks are backlinks! use it, just focus your efforts on other methods better for your site.
I agree with other comments - If most of your consumers / customers are not tech savvy, social networking sites may not do much for you, since most of the buyers will look for you on Google and not Del.icio.us or Stumleupon. But if any have comment that Google indexes then worth it. I think building up a good Digg account is a good idea.
Yes! I totally agree with all your comments guys.. but still it is a very important method. ------------------ htt://dcglobal.us/ourstaff-autocad.htm
There are not many "bad" free links. Links from social bookmarking sites will help you rank for keywords just as any other link. Granted, the smaller SB sites may not pass much PR or traffic - but it's free. Articles can be great if you are a good writer or hire a good copywriter. But some niches, like mine, get very little traffic from articles. For the time I spend writing articles, I could be improving my site, commenting on blogs, submitting to directories, networking with other webmasters, etc. But hey, articles are free links too.