One of my clients depends on online sales -- they have no external sales force and do almost no print advertising. In addition to google ad words and a little bit of online banner advertising, they actively maintain a presence, as individuals and as a company, on:

Google Profile
Storify.com
Gather.com
Articlesbase.com
Ezinearticles.com
Pinterest.com
Squidoo.com
Scoop.it
Paper.li
Linkedin.com
Facebook.com
Flickr.com
Twitter.com
Youtube.com
Blogs

And these are just the sites I know about. They also have multiple websites, with urls and landing pages that are distinct for each of their major markets. Keeping their content fresh on all these channels is a full time job for their marketing department.

Apparently it is worth it the effort as their business keeps growing. How about yours?