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Straight up? We are down to your basic Google-Alta-Fast world. And we are about to lose one of those...
You can be a pro (of the run of the mill kind) with just the three mentioned of course, but I'd add that you need to be able to craft great (acceptable) descriptions for the major directories too (Yahoo!, ODP and Looksmart).
Then, also you need to be a good strategist with the PPC engines, (Goto.com, and others), able to maximise (relevant) traffic for the minimum of costs.