Well, that was an educational wikipedia entry. I got my fact for the day from it, to be sure.

Today I learned that coffee is used to reduce soil acidity. Apparently farmers will dilute coffee four times its volume in water, a dilution which is very common to reduce soil acidity when growing tomatoes, chili peppers, blueberries and other plants prone to high acidity.

Spent coffee grounds are a good fertilizer in gardens because of their high nitrogen content. Starbucks, and some other coffee shops, have a specific policy of giving away their used coffee grounds to gardeners. While they tend to be only slightly acidic, they also tend to improve the acidity of garden soil through the same chemical processes which cause sawdust to do the same thing. Coffee grounds raise soil acidity more immediately if they are added fresh, instead of after brewing.