How do you bring a little bit of color to a space without spending anything? Group the things you already own by hue. Functional objects can also double as decor: a stack of red books on a coffee table, a basket of purple yarn next to a chair, or a kitchen shelf lined with yellow mugs...
For other examples of color-coded collections, check out these posts from AT:
• NY Mag's One is the Loveliest Color
• Flickr Finds: Categorizing by Color
• Look! Arranging Clothing by Color
• Color-Coded Shoe Collection
• Using Color to Organize Your Files
Photo: Aluminum Group from Vitra