There are a lot of standard black hat SEO methods that have been around for a while, but those that stray a little on the darker side of SEO keep busy. There are several new tactics that these people are using.
As SEO becomes a more prominent form of marketing, black hat methods are also becoming more well-known. The latest term for these techniques is “poisoning”, which I find appropriate. These SEOs will put their poisoned links (which contain malware and installations of other nefarious elements) into various places where people will find them through either particular keywords or through social media.
As a lot of people are not aware that these attacks happen, they can often give away account information, trusting that the sites they are visiting are reliable. These attacks come through Twitter and Facebook as well as through standard search engine results.
For more info on this, check out this article by Last Click News.