Good marketing is one of the most important things a business, musician, band, or really any sort of brand can do to be successful. With millions of users, social media sites such as Facebook can be a useful tool. One of the key elements for a band to market itself successfully is to interact with fans on a personal basis and make them feel welcome and close to the band.
A few examples include:
Arcade Fire's revolutionary interactive online music video, which includes Google Maps' Bird's Eye View and Streetview images of the viewer's hometown.
http://thewildernessdowntown.com/
The metal/electronica band, The Browning, has managed to drastically strengthen their online social presence and in turn musical presence among already well-established and legendary bands. One thing that they do is constantly post captioned pictures known as "memes". Based not solely on their active posting and quantity of posts, but also the quality of the produced memes help to bring a viral aspect to the band and things they post. After going viral, the band managed to steadily increase their "likes" and overall online presence. As you can see here, they gain new "likes" on a daily basis, as during the week of 6/16/12-6/22/12 they gained 2,773 new likes. Not bad.
Also, as you can see, nearly 1/5 of the people who "like" their Facebook page are currently talking about the band or sharing one of their entertaining photos or "memes". Pretty amazing.
As a result, in just a few short years, the band gained some notoriety for their music and are touring with some legendary bands aiming to draw a new, a younger audience. When done right, online media marketing can be an invaluable tool in bringing a band or a business closer with its audience on a personal level, which can be a very healthy and effective marketing tactic.

