From Nir Soffer:
With DirectionService you can easily write in Hebrew or mix Hebrew and English in the same line or paragraph, using applications like TextEdit, Mail, Keynote, and generally any application that support Unicode and system services.
Start Right to Left or Left to Right writing direction
End current writing direction and return to the default
Set the direction of the selected text
Published under the GNU General Public License
More info in the online user manual, hosted in MacMac, the Hebrew Macintosh users wiki, and maintained by various contributors: