best thing I ever found was using a 50-50 corn starch and powdered suger combination. The corn starch gums up thier guts and they end up starving but they eat it because of the sugar. The other nice thing is that the ants carry it back to the queens and eventually the whole colony dies out. The downside to this is that it can take a couple weeks to see results. The good thing is that even is the toddlers/dog/cat/bird gets into it, nothing will happen - except maybe a sugar high and a mess (which can be swept up and thrown on top of a ant nest outside! lol).
another combination i've seen is 1 part active yeast, 2 parts molasses and 1 part sugar. In this case its the yeast that eventually kills the ant i believe
The other thing to do is caulk every little hole or creavice you can find, espically those that you know ants have crawled through in the past. Sometimes when you see an ant or two roaming about, try leaving that 50-50 mixture in a pile in front of them and wait for a trail of them.... then caulk the hole and wipe up the rest of them with a bleach solution and paper towels. It takes a little work, but eventually you'll be ant free.
If you really don't want to wait... the best stuff as far as pesticides I've ever used was Ortho's Home Defence. It is a pesticide and toxic... but i bought it for spiders that have snuck into the house (have a kid who reacts horribly to spider bites and have black widows in the area) but haven't had a problem with ants since using it either. It nice because you spray it just before you leave the house for a quick grocery trip and can come back and its dry. I spray it on the base boards, along the ceiling, around the windows, and around each door, in the kid's room, around their beds, ect... and its repels jsut abotu everything for a good 2-3 months during the summer, and closer to 4 months during the winter.
hope that helps!