Adding color to their words is something that all writers strive for although I don't think many take it as literally as Rainbow Text.
Rainbow Text allows you to change the color of text to your own liking whether it's a psychedelic effect that you're after or just something a bit more exciting than plain black. It has to be said there's not much real use for it - it's more of a fun, throwaway application that could help you add a bit of something new to your documents.
To use it, simply type some text in the Rainbow Text box, or paste it in, and select your colors. Then click colorize and watch your text light up with color. The results can easily get very sickly and it's not exactly the most sophisticated app in the world but it does allow you to choose from 5 gradients of colors.
With HTML & RTF export functions to boot, RainbowText can brighten up any document, or simply make you feel a bit sick with all it's technicolored text options.