There are a number of good products for interior environmental sensing available.  I have had great success with SensaTronics (www.sensatronics.com) IT temperature monitors E4 (4 port) and E16 (16 port) sensors.  They feature both serial (RS-232) and Ethernet (HTTP) interfaces.  Easily configured they report the sensor temperatures in plain, easily parsed ASCII, with a simple HTTP GET.  My only gripe is the range of the sensors: -40° to +140° Fahrenheit (-40° to 60° C).  I hoped to use them for tracking the temperature up to 85C in an environmental chamber.

-Andrew Young,  2/25/2007