It seems there are many services that offer 150 bookmarkings, etc. Doesn't google see this activity and immediately know that it is not natural? Is it better to manually bookmark a site from time to time, with just a few bookmarking websites? Change IP?
The best way to do it is to build content that people submit to bookmarking sites themselves, I don't have to lift a finger with my site to get people to submit it to Digg, etc. If you content lends itself to this traffic, it will find you.
Building up genuine social bookmarks yourself and through other people is the most effective way to attain the kind of rankings you'd gain from this sort of activity. Paying for such services is merely a waste of time and money, and will doubtless benefit you less than if you undertook such tasks yourself.
if you have 100 list social bookmarking with dofollow, dont submit that in one day.. better you submit 5-10 sites every day.