The Media File Renamer is a WordPress plugin that physically renames media files nicely for a cleaner system and for a better SEO. Please read the description as it contains important information.
This is pro version of this free plugin Media File Renamer — WordPress Plugins
The Pro users are given a few more features like manual renaming, renaming depending on the post the media is attached to, logging of SQL queries and a few more options. With the Pro, a good process is to actually let the plugin do the renaming automatically (like in the free version) and to do manual renaming for the files that require fine tuning.