Various Manuals Online
Here's some handy bookmarks that I always have to do a websearch for and would rather have them handy here:
GNU Emacs Manual:
http://www.gnu.org/manual/emacs-21.2/html_chapter/emacs.html
The rest of the GNU Manuals Online:
http://www.gnu.org/manual/
MySQL Documentation:
http://www.mysql.com/documentation/