You probably already know that it's important to project a good paper image on your business cards, letterhead, brochures or fliers, etc. There are lots of graphic artists around who create logos and other images, but you never know what you're going to get. I've come across a great alternative: sitepoint.com/contests.
At that site, you can list what you require and specify how much you'll pay for it. Artists then submit their designs for your consideration and you decide which one wins. The typical fees listed range from $70 for a very simple logo, to $150 for more sophisticated designs, to $500 and up for the design of a website.
I didn't spot any requests for book cover designs, but if you're considering self-publishing, that might be a good one to list. Please don't make the mistake of using a friend who dabbles in artwork or who took a weekend workshop in Photoshop a couple of years ago. If there is one thing that instantly makes a self-published book stand out (not in a good way) it's an amateurish-looking cover.
I should note that as a creative person myself, I'm not thrilled by the way that this site has a lot of people doiing a lot of work on spec. In order to be more fair to the artists concerned, I would have a contest one time, use that to identify the artists who can deliver what I want, and then go to them directly the next time.