$ C-x 2 - Split screen vertically
C-u 5 C-x 2 - Split screen vertically with 5 row height
C-x 3 - Split screen horizontally
C-u 24 C-x 3 - Split screen horizontally with 24 column width
C-x 1 - Revert to single screen
C-x 0 - Hide the current screen
C-x o - Move to the next screen
C-x k - Kill the current buffer
C-x b - Select a buffer
C-x C-e - Run command in the scratch buffer
$ M-x eshell - Open a shell
M-x goto-line - Goto a line number
M-x toggle-word-wrap - Word wrap
M-x flyspell-mode - Spell checking
M-x linum-mode - Line numbers
M-x visual-line-mode - Toggle line wrap
M-x compile - Compile some code
M-x package-list-packages - List packages