I’m not very arty. But I do try. Here are some websites I find useful when creating styles and themes for websites…
Kuler - colors
Colorlovers – colors, palettes and patterns
Strip Generator – Useful tool for creating strip based patterns
Tartan Designer – Create tartan patterns
Tab Generator – Easily create tab for your website
ColorJack – Color palettes
Background Generator
dafont – Fonts
Iconfinder – Icons