When we're consistent enough, Karen's whole backyard smells like a double expresso. The cats appear to dislike that odor so they go else where to do their business. It also appears to help keep pests away.
One of our best producing tomato plants this year has produced the greatest tomatoes close to the ground. Over and over again I reach for a ripe, red tomato only to discover gaping holes on the side closest to the ground. I've never caught site of the culprit. Last night I gave each tomato plant several liberal scoops of coffee grounds to see if I could discourage predators.
Regardless, the grounds are wonderful for changing the texture of clayish soil. They add acid to the soil, which many vegetables prefer. At times we've added the grounds to the compost bin as well.
Please note that while Starbucks positions itself as a planet conscious company, it's stores are highly variable in their receptivity to giving customers used grounds. The Starbucks at Riverside and Fulton is wonderful about taking your name down and sharing the wealth among customers. The Starbucks at Burbank and Tilden once told me that they couldn't give away grounds because of health regulations. It pays to shop around and support the locations that support your garden.