I've found that the pyrethrin stuff works quite well, and you don't
have to worry so much about whether you're poisoning yourself. You
can get it diluted in spray bottles (look for the "eco" pest
controls), or as a powder in an olde tyme yellow cardboard-tube shaker
thing (think Kraft imitation parmesan sprinkles). Wet the latter with
a spray of water for best results.
And yes, a spray bottle with a dilute mix of water and hand
dishwashing detergent works pretty well, too. It just doesn't last as
long.
I've had some success with Boric acid liquid in killing colonies. It
comes in a little clear bottle, and is a sort of viscous clear goo.
Put a Post-It (tm) on the floor where the ants are coming in, and put
a dollop of the goo on it. Within hours, the entire circumference
will be ringed with feeding ants. It's really quite cool! A day
later, no more ants. It's supposed to kill the colony like those
toxic traps that don't work.