One word--Talstar. I found it on eBay. It's banned in a bunch of lib states so I figured it must be good. It got rid of my ants and according to the studies I found on it (the active chemical is bifenthrin), it has a long residual life, stays in place indoors and out, and is very safe for mammals when used as directed. However, it's very toxic to aquatic life so be careful around ponds or streams.
Ortho Home Defense Max has bifenthrin as active ingredient -at .05%. Talstar is concentrated bifenthrin - so you have to dilute. Ortho product can be purchased in stores.