Local search is a new version of the waning traditional off-line local advertising, such as newspaper ads, Yellow Pages, local radio, and, to some degree, cable TV spots.
Keep in mind that traditional media venues are actively pushing their own versions of local search. Yellow Pages directory listings, for example, can actually help your Google+ Local ranking position. So while search and traditional media may seem like archrivals, they are in some ways directly connected.
Having a listing in vertical directories such as Lawyers.com, your local chamber of commerce, and such things as your city or regional magazine’s business directory can help your overall local search presence. These get indexed by Google and are trust signals to Google of your professional local presence. In addition, reviews of your local business (like a restaurant review in a magazine) with a link to your website can pass positive local ranking signals to the search engine robots. They also can drive business since people click on them when surfing the local magazine sites or see them listed in search results. So any time an offline ad comes with an online component, it increases its value significantly, partly due to the backlink. Magazines used to throw in the online version when you bought a print ad, but now some magazine publishers sometimes have to throw in the print version when advertisers (like realtors) insist on purchasing powerful paid online ads!
There is currently a battle going on amongst local search providers. Local online advertising revenues are expected to reach $144.9 billion in 2014, according to BIA/Kelsey. Facebook, Twitter, Google, Microsoft, Foursquare, Pinterest, Yelp, Ask.com, and Apple all have offerings for local advertising. Pundits estimate that anywhere from 40% to 60% of searches have a local intent. With mobile continuing to boom, local search remains very powerful and critical to many businesses.
While getting listed in a variety of local directories and services is important, I suggest starting with Google+ Local.