The design options include tools for creating CSS gradients (to make your buttons look better, for example) and the ability to create up to 26 unique “color swatches” within a single theme. The jQuery blog features a full run-down of the apps’ features.
Another nifty features of ThemeRoller is that it integrates with Adobe’s Kuler App Service. This provides even those developers with very little design sense with libraries of interesting color sets developed by the user community there.
Once finished, developers can then download their creations for use in their own project. You can also collaborate on designs by sharing a URL to your theme with your friends and coworkers.