Press releases sites provide good backlinks also.. Just make sure your PR is relevant to the submission site.. There's no doubt that they will give you backlinks and eventually increase your page rank when you are able to get sufficient backlinks.. And don't concentrate on pure submission of PRs.. Try other methods for you get better SEO results..
Pr submission into various PR directories is always good. It is never treated as duplicate content as well
PitchEngine. Unfortunately, as of late it hasn't been working. But I had around 10,000 views in a few days for a few monsterous keywords.