I don't know how sucessfull strategy i have but i tell you what i am doing under the label linkbaiting. As first step i always need to create value. This is the starting point. after i have one at a certain URL i submit it into the digg. This is not a expressly link baiting, but since digg doesn't add nofollow to the outgoing links it has an immediate positive effect. Usually the number of duggs are in proportion to the natural links from different URLs as well. I don't say that social bookmarking would be the perfect way for the linkbaiting, but i belive that more people have the willingness to provide backlinks as a vote at digg.com, than to open their own site in text editor or somehow to add the html link code.
Here you may read a
list about the social bookmar systems which don't use nofollow.