We were working on a project recently where we needed to store colors and convert those colors to different formats (we build custom iPhone apps for studios that use Tula Software). Rather than jump right in and write our own code for this, we looked around a found a great gem called color.
We were further inspired by one of my favorite gems, money-rails, which allows you to simply mark an attribute as "money" and it does all the work for you (formatting, currency, converting to dollars if stored as cents).
We threw together a similar gem called colorizable. Colorizable gives you all the power of the color gem, turned on with a simple "colorize" statement.