Been SEOing since 2001. Still, I have those days when I check my competitors SEO tactics and think "damn, how did I miss that?".
One of my competitors managed to get a hold of a dropped domain that used to be owned by a UK bank (it was a spelling variant). This domain had the major newspapers, universities, financial authorities and "cited" papers/docs galore pointing to it.
By 301-ing these links to a brand new domain this guy now ranks in the top 10 for 100+ top financial keyphrases ... let alone all the natural traffic that must be sent through! He even signed up to that UK bank's affiliate program and placed links on the landing page!
From a £10 domain purchase this guy is probably raking in 5 figures every month straight off the bat -- has to be, because he ranks above me for several of my top phrases. From one domain purchase!
It isn't "tricks" that make me envious - but brilliantly done marketing that attracts lots of links does it - like the "Will It Blend" videos. When George Wright gave his keynote at Pubcon [searchengineworld.com] last year and detailed Blendtec's appraoch, I had a most powerful wake-up call.