The SparkFun Current Sensor Breakout is a High Precision Card that uses the ACS723 for Moderate AC and DC Current Detection Applications. The ACS723 Sensor uses a Hall Effect Sensor to Emit a Voltage relative to the Current that flows through the IP + and IP- Pins on the Board. The advantage of using a Hall Effect Sensor, specifically, is that the Circuit Being Detected and the Sensor Reading Circuit are Electrically Isolated, which means that although your Arduino is Operating at 5V, the Detected Circuit may be Operating at Higher DC or AC voltages.

Shield XBee SparkFun

SparkFun PWM Shield

MP3 Player Shield - SparkFun

Do you make time to talk to your Arduino? Maybe you should! The EasyVR Shield 3.0 is a voice recognition shield for Arduino boards integrating an EasyVR module. It includes all of the features of the EasyVR module in a shield form factor that simplifies connection to the Arduino main board and PC.

The ESP8266 Thing is a breakout and development board for the ESP8266 WiFi SoC – a leading platform for Internet of Things (IoT) or WiFi-related projects. The Thing is low-cost and easy to use, and Arduino IDE integration can be achieved in just a few steps.