Okay. Here's a good one. Something that I do (and this might be totally useless but it's a habit) is I have a priest in every province preaching long after the armies have left. In essence I garrison a priest.
Well the priest not really doing anything, gets a fever fetish and a ring of regeneration. He accumlates afflictions but his hit points remain at his max. So far this has been working out really well. And the priest being sacred is cheaper in terms of maintenace than scouts (over the long term) and typically they are sitting on a laboratory so the gems they make can be pooled. Can't do that with scouts if they are out and about.
And I just discover the Ruby Eye which weeps water gems so I'll plug a few priests with that one next.....