ognjen.kuljic

Some very useful plugins like Regenerate Thumbnails leaves old files behind, so it is good practice to clean after it.
Features: 
*Remove all unused files from upload dir (Unattached files to posts or pages), 
*Remove all leftover files (forgotten files in upload dir).

qCleanup

This plugin allows you to delete unused and leftover files from upload dir. In one click you can rid of all unwanted files and reduce space usage.

thomstark

Upload, manage, and display files from your server directories or page attachments in stylized lists or sortable data tables. And much, much more.

File Away

Upload, manage, and display files from your server directories or page attachments in stylized lists or sortable data tables.

qCleanup vs File Away