While it may not reduce the actual value, a cluttered landscape next door can detract from the positive aspects of your home. Review your local laws, which should be on file at the public library, county law library or City Hall. A typical "junk vehicle" ordinance, for example, requires any disabled car to either be enclosed or placed behind a fence. And most cities prohibit parking any vehicle on a city street too long. It also may be worthwhile to check into local zoning ordinances. An operator of a home-based business usually is required to obtain a variance or permanent zoning change in residential areas. In addition, if a neighbor's repair work produces loud noises, he may be breaking local noise-control ordinances, which are enforced by the police department. Before bringing in the authorities, you may want to make a copy of the pertinent ordinance and give it to your neighbor to give them a chance to correct the problem.
Resources:  * "Neighbor Law: Fences, Trees, Boundaries and Noise," Cora Jordan, Nolo Press, Berkeley, Calif.; 1991.