Although it is not a web site you would normally turn to for home improvement tips, Shape.com has a great article about creating a healthy home office. Here are the tips summarized:
Soothing colors - Use muted tones instead of bright colors and don't use white.
Ergonomic workstation
Fully adjustable seating
A footrest
Hands-free headset
Heavy duty paper shredder
Natural elments - Put in potted plants and fresh flowers
A calming foundation - Meaning, one of those tabletop water fountains
Proper lighting - The computer screen should be brighter than the overhead light.
One planner/calendar Read detailed explantions of each point at Shape.com. Also, you may want to check out some relevant home office articles on our site: Creating "Creating Your Home Office Plan" as well as one showing you how to make your home office more energy-efficient called "The Green Office."