You'll find a multitude of do follow SBS on Google, however, are you sure this will definitely help you achieve your goals?

I find social bookmarking gives me a good amount of traffic. I don't concentrate on it too much though as there are better options out there.

Now a days, Facebook is running awesome manner.

Digg, delicious & stumble upon are the best.

try raddit , blinklist & twitter

There are many sites you can easily search from net.I am posting few of mine.
sourceforge.net,slashdot.org, technorati.com,mixx.com, folkd.com, wikio.com, mylinkvault.com,linkagogo.com.

very impotent directory data/. High PR and good Alexa directory sharing/

I was trying Facebook and twitter but recently went into dig still working on others as it is a full time job and tiring to the eyes ..

Please check to the following url-
Social Media Network | PageUp Press Release Network