How do I add a 30 second pause between two specific songs in a play list?

You need to insert a track consisting of 30 seconds of silence.

If you don't have one handy, click here and you can download a track consisting of 4 minutes of silence.

If you want a shorter time, such as 30 seconds, use Get Info > Options and set the Stop time.

ah, great tip! THat's a lot better than what I was thinking of, which is to use Audacity.