ColourLovers has released a lovely web application called Themeleon, for your Twitter profile. You can use themeleon to customize the way Twitter looks for you and how your profile looks to others. Use any of the more than 600k seamless background patterns and 1 million color palettes on COLOURlovers or customize any of the colors or patterns to get just the right design for you.

Simply login to Twitter, choose your background (pattern or photo) and your colours. You can preview your changes instantly. Drag and drop colors to arrange the order they’re in your pattern or profile settings. Save your settings and share your work!

Requirements: -
Demo: http://colourlovers.com/themeleon/twitter
License: License Free