ground cinnamon in a shaker
Sprinkle cinnamon in a visible line along the periphery of wherever you're trying to keep the ants away. Don't know why but they will not cross the line of cinnamon. It doesn't kill them -- just makes them turn around and go away!
I've used this method in my kitchen, near my front door, and bathroom. The ants went away immediately. After about a week, I cleaned up the cinnamon and have not had to do it again. This is like a miracle to me because I live on what seems to be a huge ant pile and nothing else has worked in the past!
It's cheap, non-toxic, and worth a try if you're having an ant problem!