Frontier&Wilderness helps with Fishing.
Hammer&Nail helps with planing boards.
Stocks&Cultivars increases field fertility.
Sparks&Embers increases gun reload speed (I think).
...Do any others have further effects?
I had thought that Hunting&Gathering would increase the number/quality of forageables you can see, but I'm uncertain about this.
Needle&Thread is useful for slotting most artifacts, and a number of other skills also fall under this category for more of them being better.
Natural Philosophy helps with growing cuttings into trees.
But what about the others? Do they DO anything once you've gotten your last skill?
Does Sugar&Spice have any use after you've learned Tasty Pastries?
Faith& Wisdom? Law&Lore? Mines&Mountains? Do these have any lasting value?