Something I do as a matter of course is configure Audio Hijack Pro to enhance the sound that iTunes (and DVD Player, Real Player, you name it) produce from my laptop's speakers. Rather than getting a tinny and, well, laptop-like sound, I get something that is pretty listenable even in environments with a lot of background noice.
The key to my configuration is the use of a double-gain setting which cranks up the volume to a useful level. After the double gain, Apple's AUMultibandCompressor pulls down the level of the sound so that clipping does not arise. Rather than describe the precise configuration of AudioHijack Pro, here is a screen grab of my configuration.

