It's possible to enable Gnome sounds (after installing a sound daemon), but Gnome sounds are pretty naff. The Cleanus Gnome system sounds on debian-art I think suit the distro, and sound much nicer than the Gnome sounds. They use a wood kalimba and a metal xylophone, giving a percussive sound with a wood sustain- quite and discrete, as described.
Here's how to enable system sounds. Install the following and reboot.
esoundGo to System>Preferences>Sound>Sounds and enable software sound mixing and play system sounds. Another reboot may be necessary here. If the Gnome sounds are not to your taste, download a set of system sounds from debian-art, and follow the instructions to install. (Basically just drop them in the appropriate folder [/usr/share/sounds] with root privileges.)