You can use the Emacs Desktop library:
You can save the desktop manually with
the command M-x desktop-save. You can
also enable automatic saving of the
desktop when you exit Emacs, and
automatic restoration of the last
saved desktop when Emacs starts: use
the Customization buffer (see Easy
Customization) to set
desktop-save-mode to t for future
sessions, or add this line in your
~/.emacs file:(desktop-save-mode 1)