Manually specify color using text input and hexadecimal value is old fashion way, and you can’t guarantee user know what is mean by #ff0000. Be friendly to your user, and give them something nice. So if you need to build web application that need user to specify a color, take a look at these amazing jQuery color picker plugins.
Color Picker Plugin’s Website.
John Dyers’ awesome work on his picker using the Prototype framework. Find more information about jPicker at jPicker’s homepage.
jQuery UI colorpicker