What the author says it does
The Media Library Assistant provides several enhancements for managing the Media Library, including:
• Complete support for ALL taxonomies, including the standard Categories and Tags, your custom taxonomies and the Assistant’s pre-defined Att. Categories and Att. Tags. You can add taxonomy columns to the Media/Assistant listing, filter on any taxonomy, assign terms and list the attachments for a term.
• The Media/Assistant admin screen displays more attachment information such as parent information, file URL and image metadata. Provides many more listing columns (more than 20) to choose from. You can also add columns to display custom field values.
• Provides additional view filters for MIME types and taxonomies, and features to compose custom views of your own.
• Inline “Bulk Edit” and “Quick Edit” areas; update author, parent and custom fields, add, remove or replace taxonomy terms for several attachments at once. Works on the Media/Add New screen as well.
• Works with the popular Admin Columns plugin for even more Media/Assistant screen customization.
The opening of the plugin's own description. The full text, installation notes and changelog are on its WordPress.org page.