Comment on Link Bait Examples by SEO Dave.
I don’t use any backlink WordPress plugins. Closest would be the ©Feed Plugin : SEO Version (see article above) and the SEO Smart Links Plugin (see article above), though the second one doesn’t generate backlinks.
There’s the Twitter plugins mentioned in another comment (couple of comments up), but Twitter nofollow’s it’s links so they won’t increase a sites backlinks. The TweetMeme page like (page related to this article) has a dofollow link, so that’s a backlink, won’t add a great deal of link benefit mind you.
I haven’t tested any WordPress plugins that generate backlinks per se, I get my links the hard way :-)