This may sound ridiculous, but what if you need to signal to a rescuer?  Or more likely...what if you need to make a political statement that might be broadcast on CNN 100 times over a 4 day period? 

Seriously though, these two items won't take up much room and it's better than trying to spray paint "help" messages on the roof of your car!  We considered bringing spray paint but in 100 degree weather, we decided that it could be dangerous.  A big poster marker will work just as well.