Long answer made short, I like what I call the Kindle Social approach. If one reads a passage in a Kindle book [even the various Kindle readers, not just the devices], they can highlight it and post to Facebook and/or Twitter. So, have an iPhone app built where you populate it with various feeds from your service. Users can highlight portions or share whole posts [actually just the URL of a whole post] via several social channels and email. Finally, get a group of "marketers" aka interns, and/or temp help, to use your app to share links. Then retweet and "like" various posts that come from your tool. It is kind of like the razor blade and the handle. Personally I am a huge fan of aggregation services, but stay away from the "techie" side of it, users don't care! They are buying a 1/4" hole, not a 1/4" drill and bit.