If you have submitted to dofollow websites then surely you will be getting the result soon,always remember quantity doesn't matter its all about quality..so always post in good and dofollow social bookmarking websites, no matter if the number is less atleast you will get the good results.
In my experience I have gotten better results by posting a few high quality social bookmarks, rather than taking a shotgun approach and having someone blast low quality links out all over for me.
Specifically on a previous site I had (ezflatscreen.com) we tried having someone blast out many links to social bookmarking sites, with little results. I assume primary because they were balsting out links for many others on the same accounts. We got much better results when we spent the time to write a high quality guide, and then built up profiles on a handful of social bookmarking sites and THEN submitting our articles. And when I say building up profiles I mean filling out the profile, commenting on other users stuff, and submitting lots of articles, not just ones for your site. This takes more time, but I think you will see better results if you do this for a few sites rather than just blast articles out on a bunch of different sites with fresh accounts, or accounts which are probably flagged as spam accounts anyways. Also shortly after building up a semi active profile, I landed this article on the homepage: http://digg.com/news/technology/3D_Printer_that_can_copy_itself
Dont make so many links to your site in one day. Search engines may smell something fishy and they may think that you are a bot. So do it slowly. May be 50 links a day. And before building links check if the site is "do follow" if you are aiming for getting a high PR this way.
I have had experience with Orkut and Facebook. I have a vhdl tutorial website and I used to post my site links in Facebook and Orkut "vhdl/fpga related communities". And after few days when I checked my analytics account I got some hits from these links. Another good thing about posting links in online communities is that people who like "vhdl" only will join such communities.And so you I have a more chance of finding potential subcribers or loyal readers that way. But I am not sure of huge scale link spamming in social networking sites. I havent done that.