One quick note that should ALWAYS preceed any thoughts about running automation on your station. The FCC has something to say about you "running unattended" (as in, automation) and it's never wise to ignore the FCC. Sort of like it's never wise to jump out of an airplane with no parachute!
Anyways, the FCC's Dale Bickel has put together a handy primer on unattended operation that I suggest everyone read first.
In short, you must use proper equipment to monitor & control your transmitter gear, and this equipment must be capable of correctly any out-of-tolerance issues or...failing that...calling a live person for help (and/or shutting down things until an engineer can come out and fix them). Without evagenlizing them too much, I will say that Broadcast Tools makes two excellent devices towards this end: the WVRC-8 remote control (or its equally-good little brother, the WRC-4) and the SM-III Plus silence sensor. There's lots of other good remote controls from Burk or Sine Systems, among many others, too. A search through BSW will get you some ideas.
You'll also need to establish several procedures for having a proper control point(s) for your transmitter system, among other things. And don't forget the FCC's Main Studio rules that require, among other things, a "meaningful staff presence" (essentially two full time staff members, one of which has to be a manager-type). Don't forget you must still meet the requirements for EAS, your Public File, and the Station Log, too.
In other words, it's not so simple as just leaving the transmitter on and a Winamp playlist running. If you do that, the FCC can (and will) fine you several thousand dollars.