This came up on the BX24-AHT list.  Here is a quick easy looking environment monitoring setup that seems like a quick set up  It costs around US$60 for the top model that does Pressure, Temp, and Humidity.  Might be cheap, useful solution for those that don't want to build their own kits, but want to get introduced to weather measurement.  Probably not intended for outdoor use since it is intended for 0 to 50 C, but wouldn't look out of place in a den and hopefully it doesn't get that cold in there.
They only provide Windows software at the site, but there is linux code for it at