Powdery substances of any kind—particularly those with a strong scent, like cinnamon, cayenne, or coffee grounds—are effective ant deterrents. When they march across the cinnamon line, they breathe it in and it suffocates them. Gross, I know, but they're just ants, and anyway the ants quickly realize what's happening and beat feet. Take a few minutes to follow the ant trail and find where they're coming into your house, then generously sprinkle a line of cinnamon at the entry point. Leave it there for a week or two to be sure the ants get the message, then you can vacuum it up.
Obviously this is not a permanent solution if you've got an ant colony near your home, as we do, but it's non-toxic, it seems to work for several months, and if you buy the cheap kind (say, at Costco or a 99-cent store), it's inexpensive. Plus it smells good, which brings us to our second household trick with cinnamon...
To get rid of strong odors—like, oh I don't know, skunk—sprinkle a lot of cinnamon on a baking sheet and bake for an hour at 250 degrees. After our dog got skunked last summer, our house smelled terrible, but baking cinnamon each day for an hour gave us some relief until the smell went away. (To find out what we used to get the smell off the poor dog, click here.)
Cinnamon Sticks Photo: Flickr Member bitzi, licensed under Creative Commons