In Chinese tradition fire is one of the five elements. It is associated with the planet Mars, summer and the south, and the colour red. It is believed to govern the heart. Fire is associated with the qualities of dynamism, strength and persistence, and with restlessness and a sense of adventure.
A more in-depth description of Fire from Astrology.com: Those of you born under the influence of the Chinese Element Fire burn through life with your fierce charm, your impulsive enthusiasm and your restless emotions. A natural leader, you inspire with your decisive action and dramatic expression; people can't help but be magnetically drawn to you. Where will you lead your followers? Likely into an exciting adventure of some sort. You're instinctual, but your mind sparks with new ideas and clever solutions.
In love, you're highly-charged -- even combustible at times! Hot tamales to the core, these dynamic individuals can see straight to the heart of an issue and make it work for them. You may seem single-minded, but you just refuse to be swayed from a cause they believe to be important.
Tiger people are difficult to resist, for they are magnetic characters and their natural air of authority confers a certain prestige on them. They are tempestuous yet calm, warm-hearted yet fearsome, courageous in the face of danger yet yielding and soft in mysterious, unexpected places. They enjoy life full of challenges and unexpected events, like visiting unusual places and meeting interesting outstanding people. Other people in their area are easily attracted by the tiger's enthusiasm and course of life. Tigers find pleasure in the unpredictable, and while other people would rather make a backward step, they are not afraid to explore the new and unusual. But it is not that simple to interest the Tiger. What they really need is first-hand experience. Usually open and frank, these people are likely to withdraw and can be aggressive when trapped. As soon as the Tiger has regained their sense of security their confidence also returns, enabling them to set out once more. These people usually tend to trust their instincts, though there is another side of their personality, which assesses situations thoughtfully before they launch any actions. Their friends usually secretly admire their determination and optimism, though sometimes may find it complicated to share the Tiger's enthusiasm and can be pushed away and left behind. In spite of the fact that Tigers can be courageous and generous friends, if they are not able to achieve what they want, they can be inflexible and self-centered. So if your friend was born in the year of the Tiger, there will be highs and lows in your friendship, but the friendship itself will remain firm.
PS: neo_prodigy, I noticed that Hugh Hefner is also a fire tiger. >_>