I really think this worked. Down here I explained my attempt to use spent coffee grounds to repel slugs. Two weeks later, I'm actually impressed with the results.
The two cabbage plants I surrounded with spent coffee grounds have shown no new significant slug damage:
There's a couple tiny holes on one plant, mostly I think because the leaf touches the ground outside the ring of coffee grounds. But even so, I can deal with the occasional tiny hole.
My big surprise was the sage I'd planted. I'd bought it at Lowes in a 4" pot, so it was a pretty decent sized plant. Within two days, it had been eaten back to the wick. Every last leaf was gone and it stayed that way for weeks on end, mostly because I'd just never gotten around to pulling the plant. On a whim, I decided to use it as one of my test plants in the coffee ground experiment. Two weeks later, it's unbelievably coming back:
There's been quite a bit of debate on coffee to repel slugs. Some people claim it doesn't work, others do. I think I have to be on the side who claim it does. Keep in mind, though, that I put a LOT of spent grounds around my plants. I had a 3 lb can filled with spent grounds, and used them all on only 4 plants. I put a very thick and wide layer of grounds around the plants. So I think if you plan on just sprinkling some grounds around, you won't get results. You need to really create a solid moat.
I had also noticed slug trails across the coffee, but they seemed to go in a ways, then turn around and go back. So if your ring isn't thick enough, they'll withstand the coffee to get to the plant.
So in summary, at least until I can do further research, the coffee grounds are keepers. I've already nearly filled my second can and will have to think about which plants get the extra protection. The secondary bonus is that once I pull the plants, I can work in the grounds as an extra source of nitrogen, so there's really nothing to lose here except a couple slugs!