Adding PolyPavement soil solidifier to dirt creates a waterproof drivable surface, says the maker, providing a ready alternative to asphalt and concrete paths, drives, and parking areas. The acrylic polymer compound can be applied in different concentrations for various levels of durability; it can be sprayed on loose dirt to control erosion and prevent plant growth, for instance, or mixed with soil and compacted to accommodate heavy traffic. It costs $25 per gallon. PolyPavement, 323/954-2240,