"Spray your weeds with diluted vinegar...not only will it kill them, but the plants and soil love it. Read how here, and see the before and after pictures. I just learned about this in my winter gardening class the other day and the teacher has done it for years."
Use Old Coffee Grinds in your garden. Tomatoes love it!! They add nitrogen to the soil, boost foliage growth and deter pests. If you don't drink much coffee, Starbucks gives away coffee grounds in their Grounds for Gardens programs.