HazelHelper

Hazel watches whatever folders you tell it to, automatically organizing your files according to the rules you create.

It features a rule interface similar to that of Apple Mail so you should feel right at home. Have Hazel move files around based on name, date, type, what site/email address it came from (Safari and Mail only) and much more. Automatically put your music in your Music folder, movies in Movies. Keep your downloads off the desktop and put them where they are supposed to be.