Squishy Circuits Kits
http://squishycircuitsstore.com/kits.html
http://www.makeymakey.com/
LittleBits
http://littlebits.cc/
Snap Circuits
http://www.snapcircuits.net/
Circuit Maze
http://www.thinkfun.com/products/circuit-maze/
Chibitronics
https://chibitronics.com/
Microduino mCookie
https://www.microduino.cc/
Sparkfun
http://www.sparkfun.com
Arduino
https://www.arduino.cc/
Raspberry Pi
https://www.raspberrypi.org/
Circuit Scribe
http://www.circuitscribe.com/