My Downloads folder consistently gets large and cluttered. I considered an app like Hazel but it seemed like overkill.
I added the following alias to my .bashrc file:
alias clean_downloads="find ~/Downloads -mtime +30 -maxdepth 1 -print -exec rmtrash '{}' ';'"
which depends on the free tool ‘rmtrash’ being installed – a command line way to elegantly move files to the OSX-standard trash can.
The nice thing is when I think ’that looks messy’, I just run clean_downloads, and get a nice list of all the things that it just “trashed” – so, worst case, I can go and fish it out right then and there. Actually a bit nicer than things magically getting trashed while I’m not looking.