Some time ago I spotted a ‘Humming Bear’ toy (http://myhummy.com/). These are not only a nice bear for baby to hug but it can also generate many noises which helps our baby go to sleep. When my son had about 1-3 months we used white noise sound to calm him down and it worked perfectly.
Modules which allows you to communicate at 433MHz band are extremely cheap. Transceiver set you can get for under a 1$. Adding them up with Arduino Mini Pro (~4$) you can create wireless sensors for humidity, temperature and present them in any form you like. While working with those transceivers I wanted to check precisely
We had over ~200 STB devices (Motorola, Zyxel, MAG-250) which came from network (some working, some had issues). It’s hard to have someone test them one by one to eliminate those which had problems from units which are ok. I created a simple ‘human’ simulator which generated infrared codes to STBs to simulate channel changes.