The Vma210 Expansion Board is designed to allow easy access to the interface pins of an Arduino Nano. Each DIO pin or analog pin on the Nano is brought to an appropriate header.

In/Out Shield for your Arduino, Velleman.

This 4-digit 7-segment shield has 5 buttons that can be used as menu selection buttons or control buttons, using I2C to conduct the digital call.

Shield of relays for Arduino, with 2 channel mechanical relays and with 2 channel MOS switch , providing an easy way for applications low and high voltage control. 

This version of the Ethernet Shield is not only compatible with Mega 1280 and 2560, but also provides a Micro SD card slot for read / write

The HC-12 433MHz Transceiver is a wireless communication Module, which is based on the RF SI4463 chip, has a built-in microcontroller and can be configured by AT commands, the maximum output power is 100mW (20dBm) and the receiver sensitivity differs from: 117dBm to -100dBm, depending on the transmission speed. Accepts 3.2V - 5.5V and can be used with 3.3V and 5V UART voltage devices.

The BLE shield has the function of adapting low-power Bluetooth as a serial port , which are specifically designed for Arduino boards and compatible boards, simple to use, simply connect and a ready is ready to be used.

The upgraded Input Shield for Arduino includes a two-axis mini-joystick (with moment switch) as well as four colored buttons (red, yellow, blue, green). The reserved interface of the APC220 Radio Data Module (SKU: TEL0005) and the Xbee interface are designed to make it easy to perform the wireless remote control button controller. The shield can easily be stacked on top of your Arduino boards. It can also connect with OLED2864 and OLED9664.

Gravity: IO Expansion Shield for Arduino V7.1

Do you want to program your RGB LED strip to be a little more "rhythmic" or "unpredictable"? This RGB LED Strip Shield contains all the necessary components to create a super cool RGB LED project with your Arduino.

This RS232 shield is designed for the Arduino controller and can easily convert UART to RS232 interface.

WiDo is a WIFI IoT Node development board compatible with Arduino.

This DTMF Shield is a Dual-tone multi-frequency signaling module decoder for Arduino With it's audio connector you can decode the crazy funny noises common phones make.

A ESP32 NodeMcu WiFi CP2102 Module with Built-in Antenna, MicroUSB Connector, Bluetooth BLE 4.2, Analog Digital Converter, GPIO with PWM Functions, 12C, SPI, Etc and Supports Remote Firmware Upgrade.

Control your Arduino projects from anywhere in the world with a free app thanks to the Tuya IoT interface! Connect the Module of Tuya IoT Interface to your Arduino using the 4 included male wires. Then, connect your Arduino to the Cloud IoT Tuya simply by installing the Tuyav library, which is compatible with ATmega Chipsets (or AVR Platform). This will allow you to connect to the Tuya app via WiFi and allow you to control up to 5 outputs.

ITDB031 is a serial port BLE Module. It is based on TI's CC2541 BLE chip. With it, you can transfer data wirelessly and do remote control. It supports central and peripheral modes. And it supports remote control for the other side that is connected. You can also support custom commands when you combine it with other devices. BLE Bee is compatible with XBee. You can simply connect it to XBee.

Note: The serial interface is 3.3V, not the typical 5V, as with many Arduino boards.

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.

MP3 Player Shield - SparkFun

SparkFun PWM Shield

Shield XBee SparkFun