One of the mildly annoying things of owning a Mac laptop is how it can draw unwanted attention with its startup chime when it boots up. There was once it went off rather loudly while I was on the train and I'd imagine I must have looked rather sheepishly embarrassed. From then on I kept trying to remember to lower or mute my Mac before shutting down, but it still slips my mind most of the time. To be honest, I think that even the Windows startup chime sounds better than the one on my MacBook Pro.
So I was rather pleased when I saw someone had created a simple application (preference pane, rather) called StartupSound.prefPane that allows you to control the startup volume or mute it completely.
Intel Mac owners take note: I grabbed version 1.1b1 of StartupSound.prefPane off the MacUpdate page for StartupSound.prefPane though, as I noticed it said "StartupSound.prefPane now works on an Intel-based Mac" for that version. Wouldn't want to try the stable release version (1.0.4) since it's for PowerPC-based Macs.