Tweet, Tweet: A Crash Course in Twitter for Nonprofits

Twitter vs. e-mail and direct mail
Twitter, e-mail and direct mail all should be used together, not in competition with one another, Haydon said. But he pointed out some of the different characteristics of each and what makes each good for different purposes.

Twitter: Basically free, aside from the staff you have to pay to maintain a Twitter presence. Highly viral in that it's an open network where everyone can see each other's conversations. A good way to organize a supporter base.