By default the Nokia 5800 XM smartphone will have the camera shutter sound permanently enabled. This patch will give you a choice to disable the camera shutter sound.
The backup utility is the best feature i found in my Nokia 5800 mobile phone. Nokia provides you with a backup utility to backup all your stuff including your phone settings to your external memory card. With that you can do a *#7370# reset without any worry because you could restore all your stuff back from your backup. After the restore, everything is like as it is. Of course plus with the extra memory space i have gained.
A very well known tweak (or hack to some) for Nokia 5800 XpressMusic smartphone to increase the camera's photo JPEG compression level to 100% (default is 85%).
I am not sure if all Nokia 5800 owners notice it. There are different keypad and keyboard layout when you switches between English writing language and Chinese writing language. And the good thing about it is, when in Chinese writing language mode, the T9 prediction features still works in the alphanumeric keypad layout.