How about we keep it serious? I'd actually be interested in seeing unicorn horns used as antidotes when ground-it would create a good reason to hunt them (more so than their mod value), and make them even more valuable.
Haven't checked for suggestions re: those currently tradegoods-only products (gnomeblight, liquid fire, etc, IIRC), but I imagine someone's suggested a "dipping" production command in either an arrow/bolt-making workshop, the alchemists workshop or some dedicated place, to produce arrows with greater damage/long-term effects against enemies.
This and the above leads to imagining an apothecary workshop (with associated skills, unless the Healthcare one wanted to be used more) in which an arrow/bolt and some ground unicorn horn (or raw horn, which would be ground/otherwise processed in-situ) could preduce a health-giving medical device. Since I started down that track I've started thinking it sounds like a hypodermic, or even acupuncture, but I was actually originally thinking more along the lines of a mystical "scratch with an anti-poisonous arrow head" sort of thing. Or possibly it could be a 'kill or cure' sort of thing (c.f. the "plunging into the heart" business), for serious wounds, leaving the target insensible and needing extensive recuperation (perhaps more than otherwise needed for his/her non-mortal wounds) but immediately removing the bleeding/choking/poison (but not drowning) life-threatening conditions that they would otherwise die of in short order.
However, I'd still be surprised if this sort if thing weren't already suggested, or already on the books as a side-shoot in the Magic arc section. (I really ought to have done a search entering edit mode.