I friend just asked me an interesting question: in Leopard, can you print a document without opening the parent application? The answer, it turns out is a conditional yes.
Having never tried it, I thought; well, open the printer’s queue and drag the document in and see what happens. I’ve only tried .xsl, .doc, and .pdf. The Microsoft documents immediately open the appropriate application and print immediately. With .pdf’s it’s a different story. Pdf’s print without opening Preview or Acrobat.
That’s pretty cool.