OS X and Arduino IDE
This site has the instructions for running the Arduino IDE on OS X http://arduino.cc/en/guide/macOSX I had to install the FTDI VCP driver 2.2.18 AND reboot my Mac to get it to work. I'm running 10.9.5 and installed the latest version of the driver, which said it was for several OS X versions, including 10.8. Until I did this the IDE would hang trying to download to the Ardweeny.
I got the kit an built an Ardweeny. The only tricky part was mounting the actual chip. When done I thought it wasn't working, so I unsoldered and resoldered the Arduino a total of three times. I figured it was fried. In fact, it works fine. This is a good kit for a cheep Arduino. You need an FTDI board to program it, but they are cheap. The Ardweeny calls for having the header pins extend just to the sides of the chip and then using the chip's pins to plug into your breadboard. (Check out the Ardweeny instructions to see what I mean.) Next time I'll do that differently. Next time I will buy my own extra long header pins instead of using the ones in the kit. Then I will cut the legs off the Arduino chip and snuggle it up way inside those header pins. Then I can use the actual header pins to insert into my breadboard.
This is an excellent IoT device. We like it so much that it now has its own page in this wiki.
I've had good luck with the DHT11 for temperature sensing. It only costs $2 and works well. However, the humidity part of the sensor has often gone wild on me. It reports 100% RH when it isn't. I've heard it may need to be calibrated.