PHOTOGRAPHY AND GRAPHICS BY JAY BOERSMA

THE WEB RULES  
250 GIF images for use as horizontal rules in Web pages, PowerPoint presentations, etc.
 
Vertical blends» | Horizontal blends» | Gradients» | 3D» | Narrow» | Yokai» | Objects» | Etc.»

These images are free but there are a couple of small restrictions in their use. Click here for details.
 

If they aren't what you're looking for, try one of these clip art sites: