By following ways you can promote you company by SMM:
Create Company page over Facebook and promote it by like4like.org
Create your blogs over Blogger, Wordpress, Agryd, Tumblr, etc
Create and promote your videos over Youtube, Metacafe, Viemo, etc
Share you photos over Flickr, Picasa, Photobucket, etc
Share your blog posts over Facebook, Twitter, Agryd, Google Plus.
Submit Articles to GoArticles, EzineArticles, Newsvine, ArticleStars, etc
Share your company presentations over SlideShare, Scribd, SlideBoom, etc
Submit Press Relases to PrLog, Newswiretoday, INewsWire, etc
All the above content marketing techniques when done on regular basis and in natural way (steady pace) will offer you high SERPs and will drive enormous traffic to your blog /website.