What other social than facebook?

What social action should be used for good social marketing?

In addition to Facebook, Twitter and Digg.

Social bookmarking will increase traffic to your website, provide your site with more backlinks, and increase your site's ranking in the SERPS.
Here is a free tool that will allow you to bookmark your website's content to 42 different social bookmarking sites, all with just the click of a button: Automated Submission to Social Media Sites | OnlyWire

Twitter e LinkedIn.

Twitter
hi5
Friendster
Elgg
Myspace

Google+ is coming on strong, but still has a ways to go before it reaches the impact that Facebook provides. Maybe a few years from now Google+ will be in the dominant position.