PDF warning from CSS

In Safari (and probably other browsers too), you can apply a user-defined stylesheet to every page. Putting the following in a CSS file saved locally, then selecting that file in Safari's preferences (Advanced→Style Sheet→Other...) will cause any links to PDFs, MP3s, MOVs and RMs to be highlighted:

a[href$=".pdf"]:after { content: ' [PDF]'; }
a[href$=".mp3"]:after { content: ' [MP3]'; }
a[href$=".mov"]:after { content: ' [MOV]'; }
a[href$=".rm"]:after  { content: ' [RM]';  }
Saves a bit of looking at the status bar, anyway.