We think you'll enjoy these websites on design and color for beautiful gardens.
Look-up (by zip/postal code) your US or Canadian hardiness zone - This Proven Winners site is also an informative site for colorful annuals, perennials and shrubs.
Introduction to Perennial Garden Design, University of Illinois Extension - An EXCELLENT website for creating a colorful PERENNIAL garden. (Many of the books/tools offered at GardenColorDesign.com also incorporate shrubs, vines, bulbs, small trees and/or annuals.)
Specialty Growers - Great nursery featuring locally grown (and, therefore extremely hardy) plants. Located in Howell, Michigan and owned by Karen Bovio.
Better Homes & Gardens "Using Color in Your Garden" - Interesting lists of Best Blue Flowers for Your Garden , Best Green-Leaf Plants for Your Garden , etc.
Garden Color Design - How to Use Contrasts and Harmonies Effectively