From the (X)Emacs Manual:
There are commands for placing point and the mark around a textual object such as a word, list, paragraph or page.
M-@
Set mark after end of next word (mark-word). This command and the following one do not move point.
C-M-@
Set mark after end of next Lisp expression (mark-sexp).
M-h
Put region around current paragraph (mark-paragraph).
C-M-h
Put region around current Lisp defun (mark-defun).
C-x h
Put region around entire buffer (mark-whole-buffer).
C-x C-p
Put region around current page (mark-page).
M-@ (mark-word) puts the mark at the end of the next word, while C-M-@ (mark-sexp) puts it at the end of the next Lisp expression. These characters sometimes save you some typing.
My comments:
Repeated M-@ extends the region forwards.
M-x describe-bindings
Lists all keybindings