I just got a product announcement from Digi-Key for a new Honeywell Digital Humidity/Temperature sensor IC and it looks to be pretty low-power.   Available both as I2C and SPI and has a 14-bit ADC.  Doesn't have the pressure sensor that was also requested (so there goes barometric pressure), but may be a possibility for the other two:

http://www.digikey.com/product-highlights/us/en/honeywell-humidicon-digital-sensors/25

New Product Request and Design Idea:
The Secret Service often makes use of inductive transceiver type devices where they have some sort of apparatus on their person that receives a transmission or data-stream in some fashion.  Rather than having visible wires connecting from this device to an earpiece so they can hear the transmission, they have an inductive earpiece that fits in their ear that looks a lot like a hearing aid (though usually even smaller).

The larger transceiver device they are wearing uses a small inductive loop to transmit the signal to the hearing aid earpiece, which picks it up (optionally decrypts it) and makes it audible.  This keeps RF transmissions to a minimum (which minimizes eavesdropping and interception), works on low-power, and is undetectable to many security scanning systems.  And is stealth because there are no wires running visibly to the ear.  Worst case, all anyone sees is what looks like a hearing aid.

I am currently working on a project that will be using a TinyLily.  It will be doing some calculations based on some discrete input signals.  When the calculations are complete, it needs to relay the result covertly to the wearer of the device via a sequence of beeps or even crude speech synthesis (or wav file stream even).

Ideally, it would use a "Secret Service Style Inductive Transmitter Shield" to transmit these beeps to an earpiece.  The earpieces are available off-the-shelf.  Just do an internet search and you'll find them readily available.  But instead of their transmitter devices, I'd like to have a little TinyLily Shield be the transmitter.