From knock-your-socks-off colors of Coleus to the dreamy silver elegance of Japanese painted fern (Athyrium niponicum var. pictum), the theme is foliage. Flowers, mostly, are ephemeral. For longer lasting color with less fuss, combine foliage plants in your garden design.
Ornamental Foliage Plants, by Denise Greig (Firefly Books, $45) inspires with a section on foliage plants for specific themes and situations. Judy Glattstein’s prose in Consider the Leaf: Foliage in Garden Design, (Timber Press, $24.95) is rich with experience and example, including information about growth habits and care. David Joyce organizes plants by leaf shape and size, texture, color, and overall plant form in Foliage: Dramatic and Subtle Leaves for the Garden (Trafalgar Square Publishing, $35). The highlight of Leaf, Bark and Berry: Gardening with Foliage Plants, by Ethne Clarke, is a plant directory organized by color groups with luscious photos (out of print, but available through online booksellers and at the Miller Library).
On the web, the University of Illinois Extension has an attractive and easy to use Fabulous Foliage website for using plants with colored foliage. Give it a try.