There are two folks here running D&D campaigns that use OmniGraffle (the forum where your post is) in their RPGs. Not aware of anyone that uses OmniOutliner, though I could be wrong about that.
If you did mean OmniGraffle, searches for
RPG and
Role turned up a couple of stencils on Graffletopia; there may be others. (If you email the support ninjas, they may be able to talk the DM's out of their stencils, as well.)
We've talked about an OmniOutliner equivalent to Graffletopia, but haven't gotten around to building anything; if you'd like to see that, emailing the support folks to request that would be the way to go there, as well.
Hope this helps!