Sprinkle coffee grounds around your vegetables before you water them, you will be activating slow-release nitrogen that will help them grow faster and fuller. Slugs don't like them either! I put coffee grounds and egg shells in my garden all the time.
Tomatoes need calcium to achieve their full flavor potential. When planting tomato plants crush up (to powder) about 4 or 5 egg shells and put them in the bottom of the hole. Then plant tomato on top. They'll provide calcium and prevent blossom end rot.