origize.el
Origize centers your content at visual "origo". It inserts spaces and blank lines to center your content horizontally and vertically, making it a sweet fit to present pretty ASCII art slides that quickly respond to zoom and so on.
Origize goes well with a key-binding of your choice:
(require 'origize)
(global-set-key (kbd "C-S-l") 'origize/recenter-buffer)
Origize also provides a handy "zoom in/out and recenter" command. In the future, it might even be improved to recenter all open buffers, perhaps limited to those in a origize-minor-mode or something like that.
(global-set-key (kbd "C-M-+") 'origize/zoom-frm-in)
(global-set-key (kbd "C-M--") 'origize/zoom-frm-out)