Custom Header Images is a WordPress plugin by blackbam that provides an easy, lightweight possibility to add header images to your blog. It is simple and clean. It is easy to understand, maintain and extend. It does not make use of extra tables or buggy built-in uploads.
Simple and easy management of header images
Each possible state is covered, by using all elements of the WordPress template hierarchy
The Media Library is used for image management, images are saved by URL copy/paste (so external images can be used, too)
Requires no extra tables
Plugin homepage: http://www.blackbam.at/blackbams-blog/2012/06/25/custom-header-images-plugin-for-wordpress/