I'm on Page One! Any advice on getting multiple page one results?

Tonight I finaly reached a milestone goal with one of my primary sites. It is firmly on page one of the Google SERPS for its main keyword out of many millions of competing sites. I felt it getting close and I focused on it heavily in October. It's hovered between 19 and 31 for some time before I gave it an extremely complete examination. Thanks to everyone here for the invaluable posts that either helped directly or set me down the right path in testing.

With that milestone achieved I'm looking to add page one results accross the board for related terms.

Right now most of the secondary "set" of keywords I want to help rise in rank are between 15th and 41st in the rankings. Improvement won't be able to rely as heavily on SEO since that orange was sqeezed completely dry already. I even "micro-managed" pagerank distribution (as Matt Cutts calls it).

I'd like to keep it completely organic, the site sells nothing, but the competition is extremely fierce in this sector from sites that do sell these widgets. Even "big-red-city-widget" returns millions of pages despite being 4 keywords deep.

Is a prolonged ad campaign my only "real" option at this point? Some of the sites just behind me are huge with incredible ad spending budgets. I've resisted until now since spending to make nothing isn't wise.