Actually there are thousands ways to promote websites and I've seen members already give you great source of info. Only think that they was not mention is that all this methods require works and not much people take the words in ACTION and then fail and blame IM. Work smart, not hard!!!
As per my knowledge, 1) Article submitting to good sites with good page rank. 2) Press release submission to good sites. 3) On-page activities is far better than off-page activities. 4) Social media Optimization is very essential at present scenario. 5) Blog commenting.
few examples: to promote your website Business directories, Social bookmarking sites, Banner advertising, Pay per Click advertising (PPC), Forums, Blogs