There was research published a couple of weeks ago saying that coffee poisons slugs and snails, so spraying gardens with the stuff can keep the pests away.
I was wondering if anybody's tried this yet - and if there are any plants the coffee would harm?

I haven't seen this article, but I have read about homemade recipes for fertilizers using diluted coffee. I have been using coffee grounds sprinkled around my veggie plants as a barrier to keep out slugs and it really does work.