Emacs: Hippie Expand
- Expand current word to any matching text that occurs in existing buffers.
You need to give it a key. Put this in your Emacs Init File:
(global-set-key (kbd "C-t") 'hippie-expand)
[see Emacs: Define Keybinding]
Press once to expand. Press again to switch to next choice. Can be used anywhere, including in minibuffer.