The top five leaders in paid traffic (Google Adwords) are the same companies that lead in search, with Amazon again on top. Leading retailers don’t want to put all their eggs in one basket, and they are willing to invest heavily in pay-per-click campaigns. Clearly, PPC has worked for them because we see four out of the top five spenders are the leaders in annual sales numbers.
Regarding Link Detox, links it diagnoses as Toxic are generally fine as they're either not indexed by Google or have malware/viruses/etc., but I recommend a manual review of any diagnosed as Suspicious. I used it recently to get started cleaning up our backlinks and some legit sites and blogs were under Suspicious simply because they didn't have many links pointing to them.
WOW Brankica, cannot believe that you also includes Craigslist.org on your list! What a great post, indeed. ;) Elise add #51 email list building, so I would add #52 rss feed submission, #53 review websites like resellerratings.com, reviewcentre.com, etc., #54 blog search engine like Technorati, plus I have about 40 video websites where you can upload and share your video like break.com, blip.tv. Good luck with the contest. ;)
The term “organic traffic” is used for referring to the visitors that land on your website as a result of unpaid (“organic”) search results. Organic traffic is the opposite of paid traffic, which defines the visits generated by paid ads. Visitors who are considered organic find your website after using a search engine like Google or Bing, so they are not “referred” by any other website.