Right Click -> Create New Document, New Templates

How to add templates:

just add files to your ~/Templates directory. Name them so the name without the extension makes sense as that is all you will see in the pop up menu.

I went further as I like to "hide" dirs I rarely use.

rename ~/Templates to be ~/.templates

edit ~/config/user-dirs.dirs so that TEMPLATES line reads:

XDG_TEMPLATES_DIR="$HOME/.templates"

Logoff & back on to see the change.

Note:

• If you create subdirs within the template directory you pop-up menu will show the groupings.
• If you had previously deleted the Templates dir (as I did) the XDG_TEMPLATES... will just be pointing at $HOME

References:

• http://askubuntu.com/questions/94734/what-is-the-templates-folder-in-the-home-directory-for?rq=1
• http://freedesktop.org/wiki/Software/xdg-user-dirs/