Exposure is the key. Be a household name. The best way to do that is to find good and different ways to market. I am a huge fan of revealing a chapter and then adding the link on where to buy. If you have a good enough hook it works.
I have searched the internet for places to post and this is what I have come up with.
http://www.bookdaily.com/free and http://www.scribd.com/ They offer excerpt uploads to link to.
http://www.author-promotion.com/BookMarketingTools.pdf This is a link to 60 sites to announce the launching of a book.
http://www.mediabistro.com/galleycat/free-ebook-promotion_b52130 Another link to some useful sites to upload your promos.
http://savvybookwriters.wordpress.com/2012/02/10/where-to-announce-your-book-for-free/ More useful sites.
To the best of my knowledge these are all free. Please be smart and read the instructions for each site. Some of these may be more obscure than others, but using these links I guarantee you will, come up in more search engines, gain exposure, and reach people who don't use social media. These are writer/reader sites for the most part and therefore a targeted source.
I hope this helps! Good Luck!