There is one more song available to you in SimCity 3000, although it doesn't appear in the Music Choices section of the Preferences window by default. I am using the Windows 95 version, so I don't know if this works on the MAC version or not. Here's what you do:

In the Game\Res\Sound subdirectory of whatever directory you installed SimCity 3000 to, you will find a file called "audio.ini". Before you do anything to it, make a backup copy of it first just in case. Then, open it using notepad or another text editor and search for "[Music]". Below this heading there are sixteen lines. The first one is a description of the format of the remaining fifteen lines. These remaining lines specify which songs appear in the song list, among other things. By default, the four numbers separated by commas at the end of each line read "0,1,0,1" -- except, that is, for the last line, the one named "SimCity 2000 Theme". The four numbers at the end of that line read "0,0,0,1", because the second number is a "1" if the song appears in the list and a "0" if it doesn't. Change the second "0" to a "1" on that last line, so that the four number at the end of the line now read "0,1,0,1" like all the other lines. Save the file and restart SimCity 3000. You should now have an additional song in the Music Choices section of the Preferences window, titled "SimCity 2000 Theme". If you've ever played SimCity 2000, I'm sure you'll recognize it. Have fun!