There is even a sensor that you hook to a telephone line and when you dial it up it will tell you the temperature. Some of these units will even dial a predetermined number(s) when a set temperature is reached. I used these in computer rooms in the past to warn of over temperature events. Here is a link to one such device:
http://www.omega.com/ppt/pptsc.asp?ref=OMA-VM500-3HT