Yeah there are a ton of ideas I came up with that I never acted on like faking being a resident of a cities with GOV TLDs who have business directories on that domain. There was enough of these directories providing do-follow links that it may have been worth the effort. Seemed borderline illegal so I decided not to.

Actually, there was an article on HN recently about how easy it is to procure GOV domains by pretending to be a city. The balls of that one blew me away.

Blackhat SEO is no different than hacking. It's just exploiting systems.