Is there any sound which you don't get tired of eventually? Isn't it fun to try out new sounds? So go for it!
I strongly recommend Clixsounds as a source of interesting new Mac sounds:
They have many free sounds available at their web site. They also have CD-ROMs full of sounds, audio software, and more stuff. PPPop can also use the sounds which Clixsounds has developed for Mailsmithâ„¢.
web: http://www.clixsounds.com
email: email@clixsounds.com
aol: clixsounds
address: 7301 skylark lane, oklahoma city, ok 73162
phone: 405.721.3283
The three sound files bundled with PPPop are "Clixsounds", used by permission. Thanks!