Colorzilla offers a gradient creator tool I found to be useful in quickly and visually create gradients. They have preset that you can build upon or create your own custom gradients.
Check it out at: http://www.colorzilla.com/gradient-editor/
Visual Editor Tool for CSS 3 Gradients
Originally published at http://abou-kone.com/2011/06/15/visual-editor-tool-for-css-3-gradients/