The Official Apple blog “Inside iTunes” is a good resource for finding semi-obscure tricks and tips to really dig your nails into the more advanced features of OS X’s media player.
Did you know, for example, that every song you preview in iTunes — either on the desktop or on iOS — is saved, so you can go back and check it out later? Preview a song on your iPhone, then when you’re back home and in front of your Mac simply head over to the store and decide if you want to buy it.
This is but one example of major convenience provided by The Apple Media Ecosystem. This convenience is why I’m finding myself buying almost all my music there, even though I’m somewhat of an audiophile and music nut.