Does Social Media Optimization Help In Building Links

[MRchamps]

Does social bookmarking and networking sites really help in building links.
A far as i know it can only help in generating traffic as most of them use no-follow attribute.

Are there different ways of building links from these social sites

comments and suggestions are welcome

[RCP]

I have been working on links using social media for a month and have seen great results. I have been using:
Linkedin
Youtube
Twitter
Facebook
Wordpress (blog)
Forums
I share relevant links with people I meet on social networks.
I put my website in signature line on forum that I post regularly on.
I also submit to many directories.

[techsavvy16]

Have you tried social selling?

[bizcard]

Social bookmarking sites that are dofollow helps you in ranking for your keywords.

[MRchamps]

can anybody suggest me some dofollow bookmarking sites or or networking sites (apart from twitter,facebook ,linkedin,myspace )that can be effectively used for link building purposes