I had a small project this week where I needed a seamless vector pattern, a "tiled" pattern that can be used to fill a shape in Illustrator to create a "wrapping paper" or "wallpaper" look.
I ended up using Image 496941 for my project.
A search for "seamless vector pattern" on Crestock turned up more than 1000 patterns from other artists. What a great resource!
(By the way, if you don't know how to work with pattern fills in Illustrator, see this resource from Peachpit)