I am a huge fan of the pdf integration in Mac OS X but it does tend to churn out some huge files if you have many images in the document (which you might well have if you have been using Pages because putting images in there is so dang easy!).
But thanks to the wonderful John Gruber referencing this tip by Jerry Stratton (from all the way back in early '06) you can solve the sledgehammer compression of the pre-set reduce file size filter by making a new one of your own.
Way to go, Jerry! (Now why hadn't I ever heard about that before from Apple?)