Local Search is an important part of developing a good search engine marketing plan for many businesses.
Local search is especially important for small businesses and locally owned business that rely on a lot of walk-in customers. For example: restaurants, hair salons, co-op groceries, home decor, chiropractors and gift shops just to name a few.
This is a great chart showing the connections between various local search resources.
Source: http://getlisted.org/resources/local_search_ecosystem.pdf