Design Posters at Clip Art 'n Crafts includes line art coloring pictures of motorcycles, mandalas, Celtic knots and complex geometric designs to color. There's even a VW bus coloring page you can download free to color.
Coloring Fun for Adults and Older Kids is an article featuring G-rated adult coloring pages and projects. Learn how to make a photograph into a coloring picture, or convert a coloring page into a craft pattern at this informative adult coloring hobby page.
The Pastiche Family Portal web site is filled with hundreds of activity pages you can print and color, plus it features links to related printables and crafts sites. Find it at http://parenting.leehansen.com.