Acting on object instances on an individual basis

[Fisholith]

What are the best methods for communicating with all instances of an object on an individual basis.
For example, I believe that you can spread a number across the alterable values of several instances, and then loop through the values.

From what I have seen, communicating with all instances of an object on an individual basis seems to be one of the most useful ways of interacting with objects, but at the same time it also seems like there is no simple way to achieve this without some sort of work around.

Anyway, I’m just trying to find out what methods exist out there for doing this. I’m looking for anything that works.
i.e. Methods that use Alt alterable values, methods that use fixed values, or methods that use some special object.
Thanks.

[Joshtek]

For most things I'd say the loop method is the best. When you do an action on an object it does it for each instance separately, tho.