Best advice my first design teacher ever gave me. Take a screenshot of your computer screen with your desired browser maxed out. Move the screenshot into Photoshop, clean it up, save it as a template and when you're coming up with design ideas, use the blank space as a canvas for your site. Still effective today.
This is a template for Firefox users, resolution 1280x1024, using Microsoft Windows 7. I cleaned up my status bar.
For use in Photoshop CS+. No you don't need to credit me for use, but a thanks on my page would let me know it's used.