An oldie but goodie from John Gruber that I just discovered while looking for ways to soft-wrap text in BBEdit:

tell application "BBEdit"
    tell window 1
        if not (soft wrap text) then
            set soft wrap text to true
            set soft wrap mode to page guide
            set show page guide to true
        else if (soft wrap mode is page guide) then
            set soft wrap mode to window width
            set show page guide to false
        else
            set soft wrap text to false
        end if
    end tell
end tell

I use BBEdit all the time for editing text. LaunchBar fires the script for me.