editing primitive starting parameters

i’ve looked through the essential blender book and tried searching here and can not find this. when you add a new mesh, say for example a cone, once it’s been added to the scene is there a way to edit the starting parameters that you choose when you first added it? it seems like such a basic thing to be able to do but i can’t find this option anywhere.


That’s one of the big things that they’re working on for 2.5… being able to change parameters after you do something rather than before.