Additionally, if you don't want to store all your music on your macbook, just set iTunes to NOT synchronize when you plug in your iPod, and you can play music from your iPod through the iTunes interface.
Just don't under any circumstances, setup itunes to auto-sync with your iPod unless your music is there. In my own experience, I plugged an iPod into an iBook with an empty iTunes library, and iTunes cleared out my iPod in an attempt to "sync" it. I had to use file restoration software to recover my music, and even then I lost some. Just a word of warning...