As long as your committing a half hour to SEO, I’d add that your would do well choosing “other verticals” based on your own expectations for that new vertical to intersect (as some future point) with your own. The insight you use to predict that, whether the prediction is right or wrong, will lead you to see parallels and thus opportunities for SEO. If you discover such an opportunity, you can blog your findings on a new blog somewhere, linking out to your existing sites as well as the sites in that (new) vertical… discussing those aspects that may or may not someday intersect.

You get your 30 minutes in, but you also may get noticed for your insights, will build co-citation links for your sites, and just may differentiate yourself from your competitors in a very positive way.