2. Remove a certain tag from all posts in one go.
3. Add a certain tag to all posts already tagged as X.
4. Rearrange the order of tags in a single post or multiple posts without having to delete them first.
5. Display a list of all tags that are currently in use, somewhere on the dashboard, and make them clickable.
6. Search for posts that either have no content source (the field was left blank) or contains a source URL that is a Tumblr blog. This makes it easier to reblog and source posts that aren’t properly sourced by the OP.
7. Find and return a list of duplicate posts, i.e. posts that contain the same image/text, whether uploaded by different people or not. This one’s probably hard to do.
8. Search image posts by format: JPG, PNG, GIF, etc.
9. Differentiate between original posts and reblogs, and make them searchable by tag. Say, if I want a list/page of all originals/reblogs on my blog that contain the tags X, Y, Z, etc.
10. WYSIWYG text editor in the Tumblr app for smartphones/tablets. Manually inserting the HTML for each link is a pain in the ass when you’re on the go.