In the past 25 years, my family has lived in 3 places. Each has afforded the opportunity to make built-in bookcases and/or wall units. 

Please click on each thumbnail to see a larger image and description. These are examples from our current home:

• The first two are bookcases in our living room. They are built entirely of select pine - no particle board or plywood. Each shelf is mounted in the uprights and strongly supported - no clips or tracks
• The next four show the three design elements of our walk-in closets: double closet poles, single poles with shelves, and racks of shelves. Everything is wall mounted and off the floor, with vertical pieces suspended from and resting on cleats
• The next two are display shelves in the front hall and den
• The last two are an enclosed window box (there are two) for ground-level egress windows; they meet the building codes requirements for minimum egress dimension and the french cleat wall storage in the workshop