Meet 1btn: an open source, WiFi connected internet of things button that lets you complete tasks with the click of a button. It can be used to send an e-mail, tweet for you, or interact with IFTTT. The device has a rechargeable battery. Since it uses WiFi to connect to the Internet, it does not need a native app to work.
1btn uses the WiFi System-on-Chip (SOC), ESP8266. It comes with a 3D printed hexagonal casing. You can use it to learn about home automation, turning on/off lights, locking doors, and more. You can get yours here.