Alexa rankings prove why web 2.0 site traffic will help your SEO efforts.
Just did some research in looking through the top 500 Alexa sites. Not too surprised to see all the more recent approaches to getting both backlinks and traffic here.
While backlinks have been devalued lately, incoming traffic is more valuable. Some studies of how things work showed that many are going to Doc Sharing and Video sites to get their traffic up. (And use of embedding gives traffic to those sites, which raise their rank and so return with more traffic...)
As I saw what was unfolding, I kept track to see how it panned out. Now you can see that there is a definite trend happening...
The use of remote "free" blogs to get backlinks is old hat, but shows to be completely viable - particularly if your blog shows up as "featured" through their on-page search.
Video and images, along with documents are a more recent SEO effort, changing tags and descriptions to get your keywords. Docs often have live links, particularly the ones which are embedded. (Not for the search engines, but for the viewer.)
Hope this helps your approaches to getting your web-pages ranking better.