QBOX  do not waste your money on this.

I find that I have to constantly re-enter the searches for them to work. and you can not narrow down your searches geographically.

but most important is this service is already free! just use the rss feed on the bottom of craigslist to send results to your Safari bar or Mac Mail account.

this works much much better than Agent Craig. AC is a good idea but they really did not put the time in to develop it. I am sorry that I wasted my money.  
(Version 1.05)