How can I add reminders via the command line?
Here's another version that allows you to set the title, end date and time via command line arguments.

#!/usr/bin/env bash                                                                                                               
# Make a new reminder via terminal script                                                                                         
# args: remind &lt;title&gt; &lt;date&gt; &lt;time&gt;                                                                                                                                                                                 

osascript - "$1" "$2" "$3" &lt;&lt;END                                                                                                        
on run argv                                                                                                                       
    set stringedAll to date (item 2 of argv &amp; " " &amp; item 3 of argv)                                                               
    tell application "Reminders"                                                                                                  
        make new reminder with properties {name:item 1 of argv, due date:stringedAll}                                             
    end tell                                                                                                                      
end run                                                                                                                           
END    


So if you were to name this script "remind" and give it executing privileges (chmod 755 remind), you could do this:

$ ./remind "Go to grocery store" 12/15/2013 10:00:00PM