http://www.emacswiki.org/elisp/goto-last-change.el allows you to move point through buffer-undo-list positions.
If anyone feels ambitious I’d like to suggest that this function be modified (or a new one written .. perhaps called goto-next-undo) to be a bit more undo-friendly. I think it would be quite useful if one could use this function while undoing. That is, after hitting the undo key, being able to hit the goto-last-change key to see where the next undo will occur and not have the operation cause undo to reverse directions and undo my last undo.
I placed this question on Stack Overflow: "Is there emacs capability for visiting last edits?"
Basically, it would be awesome to get a similar function that works across all buffers.