WP-Sweep allows you to clean up unused, orphaned and duplicated data in your WordPress. It also optimizes your database tables.
Clean Up Booster is a High quality plugin which allows you to clean WordPress and optimize database along performing other vast security functions.
Deletes all unused tags, handy tool if you want to start over with a quick clean blog.
Clean up unused images and other files from your uploads folder.
WUCO aka WP Ultimate Cleanup & Optimization, a free easy to use yet effective plugin designed to help you keep your MySQL database clean.
This plugin will help you to manage your upload folder, identify useless files and remove them and save space.
iTrasher allows site admins to delete unwanted or unused images.