For OS X there is also PDFPen
http://www.smileonmymac.com/PDFpen/. It allows you to do much more than preview. Then again, it is not free. However, if you do alot of PDF editing it does seem to be well worth the $50.
There is a ScreenCastsOnline episode on Preview. I learned alot about it from that.
http://www.screencastsonline.com/ind...45-preview.php
This is a member only show... but for Mac owners, I highly recommend an SCO membership.
BOb