I've spent quite a bit of time since the release of Xbox in 2001 playing what I consider one of the best games ever - Halo. I have a treadmill in front of a game machine (most recently it's actually a powerful PC built specifically with one goal in mind - playing Halo), so every day I set it to 2 MPH, 12o incline, and spend 90 minutes playing the game. It results in 2000ft elevation gain, and 1000 calories burned.
The game is so good because it's realistic. Not only it sports a universe where objects respond to your actions in a way you'd expect them to in a real world. You also see groups of people behaving in a way that's not dissimilar (psychologically) from the real life. The behaviors range from outright chivalry to deep sociopathy.
One of the principles I learned in the game that I apply in regular life can be formulated like this - "Find your strength and abuse it. Don't suck at everything else, but do find every opportunity to play to your strength."
Most of the Halo players are universalists - they are equivalently good (or bad) in all situations and with all weapons. Occasionally you would meet a true professional - a sniper, a Banshee pilot, a Warthog driver. These people are REALLY good with a particular weapon or a skill.
A sniper will pick you out from the remote corner of the player field, but also blow you brains out with his rifle from merely a few steps. A master banshee pilot can evade homing rockets, making the only weapon that is worth anything against the vehicles useless. A driver can splatter a row of an advancing infantry in one big swoop.
A team that has any one of them on their roster is unbeatable.
The only way to win against a team like this, as I learned, is to deny the professional player his or her tools. If it's a sniper, steal his team's sniper rifle. If it's a pilot, grab their Banshee before he does. You may not be as good at either of them as the adversary, but the difference would still be huge. Because most of the time, the professional player would be pretty bad with other weapons, vehicles, or situations.
Find your strength and abuse it.
In a real life, this statement goes again commonly held wisdom that the best person is a well-rounded person. Microsoft's newest review model for example details on the order of 5 competency classes, mostly orthogonal (yes, a 5-dimensional space!), in which a person must succeed to advance in his or her career.
I had many a junior developer coming to me and saying "I love coding, but my manager tells me that to get to the next level I must find a way to work with other teams, so I need to drop what I am doing and find an intergroup project."
It goes the other way around, too - I have seen some reasonably good people managers being driven insane because they were "not technical enough".
I think that an insistence on a well-rounded set of competencies almost guarantees mediocrity in the long range.
Bill Gates has not become what he is because he is a well-rounded person. In fact, Bill is a very uninspiring leader, probably a terrible team player, and certainly would not have moved much beyond a dev lead within Microsoft's new review model. But he is a brilliant strategist, and a great technologist, and he found a way to exploit his strengths, while hiring other people to compensate for his weaknesses.
I don't think much people care about interpersonal or leadership skills of Guido van Rossum very much (I am not trying to say he hasn't them, just that they are unimportant). He got to where he is - a designer of wildly popular computer language - by being a brilliant coder, and a great computer scientist.
Neither did "the cookie man" Lou Gerstner achieve - against all odds - his amazing turn-around of IBM because he was a great technologist, or indeed knew anything about engineering or any other aspects of IBM business.
Whenever you look - from Heinrich Scliemann to Albert Einstein, the people who left an imprint on the civilization had glaring deficiencies in many, many, many things. They had one or two overwhelming strengths, and the courage to do what they do best, rather than what they are told.
So for the individual contributors, I would repeat again and again. "Find your strength and abuse it. Don't suck at everything else, but do find every opportunity to play to your strength."
And for the managers - "Find what your people's strengths are, and put them in positions where they can abuse them for the good of the team."