Space efficient web page layout is an often desired, but rarely achieved design goal. The problem comes from one of the main side effects of the web technology - you never know how big is the screen of the viewer. Some "solutions" you might encounter are

• old-school "best viewed at XxZ resolution"
• fixed width layouts, centered on page - a lot of blogs use that
• fixed width layouts, left or right aligned - have a look at the bbc website
• using the "defect" as a design feature

You can find a lot of good examples for all of the above at the csszengarden.