Planet13 - 3:28 am on Dec 2, 2011 (gmt 0)
One method that is more "passive" than the others...
Allowing visitors to "mash up / personalize" your content
I think Amazon and some of the big retailers allow users to create their own suggested items list (I forget what they call it). Then amazon encourages those people to share their lists with friends, relatives, etc., though their blogs and facebook pages.
So if somehow you can get visitors to feel like they have "ownership" over a small section of your site, and you encourage them to promote it, then you can apparently get some links (according to some of the backlink checking I've done).
They probably don't get GREAT links, but once the initial setup is done, their probably isn't a whole lot of work that needs to go into it.
I think that ecommerce sites could probably also do this with "wish lists / gift registry" where the visitor has a stake in publishing that information.