One of the handy built in features of OS X (Leopard) is Quick Look. It has built in plug-ins to view PDF files, images etc. without needing to open the application. That's fine if your only using the apps that Apple ships it with, or makes - but everything else needs a plug-in. I was disappointed that such a neat feature couldn't be put to better use for times when you don't really want to open the inDesign...