If your website is looking a bit stale, but it's not yet time to invest in a complete redesign (and all the work, strategy, and writing that goes with that), you can make some small changes to your site that make a big difference.
One of the easiest things to change is your page background. If your site does not extend all the way to the edge of the page, then you can just go into the main BODY tag in your HTML and either change your background color, or add a background pattern image that will add some visual interest. Just make that quick change to every page of your site and you're set.
Here are a couple of examples of background patterns being used on websites:
The blue bubbles at http://www.uplevelstrategies.com/
The green diamonds at http://www.elf-design.com/