I have also a number of backlinks to the sites- a mixture of High PR PDFs filesharing sites with the URL embedded in the document.
I have a Pinterest board which is packed with related images, and has the keywords in many descriptions of the pins, though Pinterest appears to be nofollow, I know boards themselves can rank.
I've pinged my links to various places like Pingler, a few social signals are in place too (linked Facebook and twitter pages).
So what else can I do? Content is not a problem- I also know from reading the Moz guides the best way to place KWs through structure of posts, pages etc, so that's being worked on.
Do people use Youtube, Web 2.0s where content is syndicated, keen to hear other's thoughts?