I think Hazel is a great idea, but I'm having trouble finding practical uses for it. A short search revealed the below pages, but I still didn't find anything compelling.
For me, Hazel works best when I'm using it in conjunction with other tools. On its own, in can seem a little lackluster or underwhelming, but when combined with other applications or used as the 'glue' between them it really shines.
One of my uses is to automatically organize PDFs of schedules from work. I've got a Dropbox account, and make use of Send to Dropbox to allow me to email attachments straight into my Dropbox. The issue is that they're not always consistently named, and I don't feel like manually renaming them. I have Hazel watch the destination folder, and when a PDF arrives, whether its named 7.30, 7/30, 07-30, etc, it automatically renames it, moves it to folder with other already acted on files, and archives away old versions. The result is that I have a nice archive of schedules, all consistently named/sorted.
I use Hazel to help out with video encoding/tagging tasks. After encoding a file, Hazel picks up on it in the destination directory, and automatically renames it based on a consistent naming scheme. Once it does this, it applies a label to the file, and moves it to a new folder where files awaiting metadata live. Any file here gets passed through an automator script that adds some basic metadata (show type, year, etc) before passing it into iFlicks for the final touches before throwing it into iTunes.
It also handles more mundane tasks. Some trackers list .torrent files with a .txt extension. Hazel will monitor the downloads folder, and if a file with a .txt extension shows up, it checks the file's "Where from" attribute, and if it matches a trackers website, it changes the extension to .torrent and moves the file into my Torrents directory so that Transmission can add it.
There are times when I don't need to see my Bootcamp volumes mounted on the desktop. Hazel can check for this volume, and it if sees it mounted, it'll run a shell script to unmount it.
Some use cases of my own:
Synchronizing my kindle in 1 click: instapaper.com has a setting to send articles daily to your kindle mail adress. But sometimes I want to force an upload of all unread articles just now. I just have to download the mobi file from instapaper then Hazel takes over :
- Move ebooks rule detects .mobi in my Downloads folder and move them to an Ebooks folder in my Public Dropbox account.
- an ifttt.com rule is triggered and send an email to my kindle adress with the .mobi as attached file
Turning my Mac mini into an automated media center: my mac mini sits under my TV and is not supposed to be controlled by mouse or keyboard. Hazel is the central part of my setup that enables complex actions to be executed without user interactions. I wrote a blog post on this specific subject.