Extension Manager

NameDocsDescription

Admin
Use an additional stylesheet on certain holidays
Recount / Rename / Etc

Feature
Allow users to make comments on images
Show a list of uploaded posts
A simple wiki, for those who don't want the hugeness of mediawiki

File Handling
Bulk add server-side images
Bulk add server-side posts with metadata from CSV file
Allows bulk exporting/importing of images and associated data.
Handle MP3 files
Handle JPEG, PNG, GIF, WEBP, etc files
Handle static SVG files.
Handle FLV, MP4, OGV and WEBM video files.
Regenerate a thumbnail image
Allows people to replace files for existing posts
This extension allows admins to resize images.
Allows admins to rotate images.
Allows admins to automatically and manually transcode images.
Allows admins to automatically and manually transcode videos.

General
Edit the alias list
Adds autocomplete to search & tagging.
Turns BBCode into HTML
Renders common elements (thumbnails, paginators) in a way that themes can override
Bring a specific image to the users' attentions
Allows displaying a page with random posts
Show various bits of system information

Metadata
Provides several automatic tagging functions
Allows bulk setting of parent-child relationships, in order of manual selection
Allow images to have metadata locked
Allow images to have owners assigned to them
Allow posts to have relationships (parent/child).
Allow images to have sources assigned to them
Let tags be split into 'categories', like Danbooru's tagging
Add or remove tags to the editor via clicking.
Allow images to have tags assigned to them

Moderation
Provides query and selection-based bulk action support
Report posts as dupes/illegal/etc
Allows the admin to set min / max image dimensions
Keep a record of source changes, and allows you to revert changes.
Keep a record of tag changes, and allows you to revert changes.
Provides "Trash" or "Recycle Bin"-type functionality, storing deleted images for later recovery