As far as this post is concerned, I would be referring to Blender's 2.49 version, or probably earlier ones which has the same feature. The other day, I accidentally came across a little nifty feature that's common among paint/image editors and or applications. Enough rambling, it's the Undo History (as the title has already suggested) ^_^
I believe this could in fact save you a lot of time especially in your modeling phases. Check the image below.