There are two hardware elements which I have always been mildly disappointed with on the iPhone; the camera and the sound quality of it’s speakers.
For the latter, a company called Ten One Design have announced a product called SoundClip which increases the sound by about 10db between 6kH and 20kHz. Soundclip acts as a conical deflection chamber that directs sound from the iPhone towards you, increasing both sound clarity and volume.
As tech blog Crenk points out, the device is ideal for movies and music – however for gaming the device gets in the way and more of a nuisance.
You can buy it direct from Ten One Design at $7.99, however for overseas shipping the price doubles to $14.99