Automatically categorize downloads?
You can do this with Hazel:


  Create rules to automatically keep your files organized
  
  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.