Multisite Featured Image
With the WordPress Multisite Featured Image plugin you can create “featured images” for each site in your network.
Free
You won’t have to come back tomorrow to get these plugins for free. *Please note, there will be a one time processing fee.
WP.com Image Feed Widget
WordPress Image Feed Widget plugin allows feeds with image embeds to be shown in the sidebar of your site, or anywhere widgets are allowed in your theme.
SEO Media File Renamer Pro
SEO Media File Renamer Pro is a plugin that gives you full control of your uploaded WordPress media files.