Un-posing to re-model?

Hi i’m a new guy and was hoping for a little help.

I’m building a character to pose for a static image. I’ve modeled a basic version, rigged and posed him but now i want to go back and re-model particular body parts.

Is there a way i can have his head, for example, snap between its posed and original unposed orientation? I want to be able to model useing my numpad 1,3,7 views where eveything is orientated to X Y and Z,

Thanks…

In 2.49 under Armature tab there is button “Rest Position”.
In 2.5x this button is placed under Skeleton tab.

Cheers mate, perfect!