How organize uploaded media in WP?
Best is Enhanced Media Library plugin http://wordpress.org/plugins/enhanced-media-library/ It's adding as many category/ taxonomies you want. Works just great. You can filter media everywhere, plus have the categories in the menu choices, can be usefull also.
As of October 2015, WP 4.3.1 I have found only two plugins actually affecting image locations as in “folders & subfolders”:
Custom Upload Dir, but as the name says, just on upload. You can work from your %post_slug% or %categories%, upload your images in the context of these post/pages, and this tool will form subfolders from it. Which is great, SEO-wise.
Or you just even ignore all that and mandate under “Build a path template” i.e.
travels/france/paris-at-night
to upload to that subdir of your WP-Uploads folder. (Of course you'd have to keep changing for the uploads to follow. Limiting my overall faith, that this is a stable long-term tool, despite 10.000+ active installs).Media File Manager allows to move already uploaded images and changes the paths in posts and pages using them accordingly. Its interface reminds of “Norton Commander 1.0” but it does the job. (Except for folder renames and deletes. So if you want to rename, better move images to a newly namend folder, then manually deleting the old.)
All of the following do NOT do the job:
WP Media Folder is NOT changing actual direcory location, thus not actually changing paths to your images thus also not affecting image URLs. Despite its name, Folder is just their visualisation of yet-another-taxonomy. I invested $19 to learn that.
Enhance Media Library is big, free and very popular (wordpress counts 40.000 installs) but is also not changing physical location and (thus) URLs. ➪ Thus the accepted answer is in my opinion wrong.
Media File Manager advanced appears gone and is deemed dangerous!