Diatomaceous Earth. Ants hate the stuff and it's totally non-toxic. You can actually eat it (the food grade variety anyway).
Everyone should have a bag of it, can be used for many things, including treating certain kinds of worms in pets, dusted onto the coat it deals with fleas and is highly absorbent so can be used to absorb spilled oil/liquid.
These people sell it, I've heard that apparently some Bunnings outlets stock it also.
http://diatomaceousearthonline.com.au/