"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."
Moss Graffiti: Mix yogurt, water and live moss in a blender, then paint onto a wall. Moss will grow in the shape of whatever you painted. Just remember to spritz it with water every once in a while to keep it alive.