I really love fact that zabbix is able to store global scripts that can be run from maps and Monitoring views. But i think it will be a nice idea if user were able to define parameters for it's script.

Mostly when the script is just a command with some parameters it become quickly boring to create a new script for each variation of a parameter.

For example let's consider a script (for sheduling a shutdown or a restart) which will be run on windows agents (this restriction can easily be accomplished by specifying a windows group while creating the script). If we want to shedule the shutdown in 5m it's a script, 10m, it's another different script. I agree that the example may not be convincing enough but i hope you'll get what i'm talking about.
So i think it'll be better if while creating a script user can choose from some types of script: 'Default' or 'Dynamic'.

Then when user picks Dynamic he will specify some parameters which values will be prompted to him when he will try to execute this script later from the front end.

Back to my shutdown script: shutdown /s /t 300

PS: 300 is the actual value of parameter /t  

User will then have to specify /t as a parameter. Then any time when he will be executing this script he can input any number for the /t.