As always, these are my own opinions and musings and not official Intel positions or recommendations.
I love Mathematical Game Theory and one of my favorite areas is the "iterated prisoner's dilemma" which models the human behavior to cooperate and to cheat (defect). Variations on the game and strategies give us concrete ways of describing numerous social behaviors, including con-men, free-riders, and reputation based punishment systems.
The basic principle of the game is simple and played between two players, if both cooperate with each other, they win a reward. If only one of the players defects, that player wins an even better reward and the other player gets less of a reward. If both players defect, both players get a reduced reward. Thus, it is advantageous to a player, if the other player can be convinced to cooperate, but advantageous to themselves to defect. The game is designed so the advantage for both cooperating is the best long term reward
One effective strategy for the iterated version is called tit-for-tat. In this strategy, the player begins by cooperating as that gives the optimal payout for both players [summed together] over the long run. If the other player attempts to cheat and raise their score at the expense of the player by defecting, on the next round the player defects and punishes the other player. That gives a disincentive for the other player to defect, because the other player knows they will be punished for defecting on the round after they defect. If the other player returns to cooperating, the player stops punishing them. Each time the other player defects (tats), the player responds by punishing them (tits) and thus the name of the strategy.
Twitter as a form of word-of-mouth communication is a cooperative system. If you like something that someone else tweets, you can amplify that message by adding your own voice to the message. The normal way of doing this in twitter is called a retweet (RT). The idea is that some people follow what you are saying who might not have followed (or just not have seen) the message the original author wrote. Thus, by retweeting the message, you are emphasizing it.
As a cooperative system, twitter can be described as a gift economy. In a gift economy, a positive form of tit-for-tat is a very effective strategy. It is often called "give to get" or quid pro quo. In give to get, you perform a favor (cooperate) for someone in hopes that they will return it. In twitter, this can be retweeting someone's message, answering their question, or introducing them to someone who has similar interests. In return, you hope they will do a similar favor for you.
Of course, one of the things about a gift economy is that it is based upon "gifts", things one gives freely away. That is a key aspect. If one gives with too much expectation of receiving a precise, fair, equivalent amount back, one will tend to be disappointed. Only by giving generously without keeping tally can one reap the benefit of the strategy.
The nice thing is that the mathematical model of game theory shows us just that effect. In games, where one of the players is playing tit-for-tat and the other has a propensity to cheat, the total score for both players will be lower than if the other player is totally generous.
Generosity is its own reward, especially in systems where cooperation plays off.