Mine is:
Understand the Long Tail. Most search phrases are unique, so there is a LOT of traffic to be had from non-competitive phrases. Choose many keywords from your niche, and write a page on each. Watch your logs. If people arrive under a particular keyword term you've missed, add a page to your site using that keyword term. Repeat.
Sure fire way to get a lot of traffic that is largely immune from shifts in ranking.
http://www.longtail.com/the_long_tail/faq/index.html