<form action="http://maps.google.com/maps" method="get" target="_blank">
   <label for="saddr">Enter your location</label>
   <input type="text" name="saddr" />
   <input type="hidden" name="daddr" value="Cullen Blvd, Houston, Texas 77047" />
   <input type="submit" value="Find your path" />
</form>