Do all these social bookmarking sites can be taken as a back-link resource ? Does Google spiders crawl through those links or they are only taken as internal links ?
almost all my social bookmark page are index http://www.google.com/search?hl=en&...:en-US:official&hs=tOb&q=samskpun&btnG=Search
The real test is to see if the social sites are in fact providing backlinks to your site. Being indexed is one thing, but counting as a link is another. For instance almost all links from delicious are tagged as no follow links.
They are usually. But they can drive traffic and they can also make your site better known so you get more natural links to your site.
lot of keyword is not claim in those social bookmark site. tag your site with different tag so your have more chance to be found
That's probably a good point. I used to think it was a better idea to go for the popular, but that one person looking for a keyword that has NOT been tagged often yet is probably highly valuable.
Magnolia and Simpy are pretty good for building backlinks .. Delicious doesn't really show up as backlinks to my site..
There are several of them that gives you real backlinks. You can see a big list of social bookmarking sites at http://backlinkstore.com/social-bookmarking
You are much better off link baiting blogs than you would be trying to get backlinks from social networking sites. Social networking sites are pretty good just for getting direct traffic though. Every now and then I hook up with women I meet on MySpace. Great fun.
Some do count and some don't - look at the page sourse and see if it's got a nofollow tag. Someone should really come up with a list of SB sites that give you credit, that would be valuable.
Someone already has : http://forums.digitalpoint.com/showthread.php?t=195410 But most of the updates will done on my forum now as I don't want to bump an older thread.