Hi Brankica, Really hard pressed to come up with #51 here as it's such an extensive list. Quite a few of my customers have had success driving traffic and awareness with Groupon recently. By setting up special offers they are able to get real people through the doors too. Just by asking people to quote the coupon code when they fill in the contact us form, or when they pick up the phone, it's a great way of tracking success. Still getting my head around how this could be used my an online only business, but for a brick and mortar with a web presence it's a nice little option.
AllRecipes: This site is one of the larger recipe-focused sites on the web, and it also has a reputation amongst foodies for having a ton of comments about “this recipe was terrible, also I made X, Y, and Z substitutions.” You, too, can take advantage of these recipe comments to promote your own changed version of the recipe, if you have a cooking blog.
To do this, I often align the launch of my content with a couple of guest posts on relevant websites to drive a load of relevant traffic to it, as well as some relevant links. This has a knock-on effect toward the organic amplification of the content and means that you at least have something to show for the content (in terms of ROI) if it doesn't do as well as you expect organically.