I found an excellent site with some great wallpaper images.
The link is "http://www.vladstudio.com/wallpapers/
This will take you to the main wallpapers page. Clicking on an image brings up a larger version of it. Then below the image are links to various different image sizes. Right below those links there is a button that says "Download for Mobile Phone." Clicking this button shows a menu with various different small screen sizes. All they way to the right then is the 640x480 link.
Some of these images are just amazing.