[QUOTE=Mirek Komárek;4439960]checking for user agent is good, when you want some script run just for you,QUOTE]
That's a good idea. Just change the user agent so it contains something that will uniquely identify your browser eg. add your name into the user agent.
It doesn't stop someone else overriding that so as to get it to run anyway but it would prevent casual visitors from accessing it by accident.