Sometimes it would be very nice to be able to add connectivity to your Arduino/Freeduino project. The Adafruit Ethernet shield kit lets you add network connectivity!
LEDs are cool. Low power, bright, colourful, and now fully networkable! Use the BlinkM Smart LED to dynamically illuminate your project!
The RS-485 wiring standard & protocol is very well established for industrial applications, and the Devantech USB-RS485 lets you bridge this easily to your PC's USB port!
Using the FT232RL, the Arduino Serial USB Board shows up as a com port allowing serial communication to and from the Arduino Stamp or any other serial device.
Designed to replace RS232 serial cables. A Bluetooth Class 1 device with up to 100m range (free space). Easy to setup and configure using LM Technologies LM049 user interface.
The Serial Adapter for BS1 will enable you to program your Basic Stamp 1 in Windows!
The USB to RS-232 Converter is a self powered usb to DB9 serial port adapter.
It is the most easy and reliable way to connect the Xbee module to a PC via USB port.
The Synapse SNAPstick is designed to be a compact and easy way to connect a PC to a SNAP wireless network via your PC USB port.
This is a simple SD or MMC adapter card. It allows you to interface with any microcontrollers. It is perfect for mass storage, WAV/MP3 player and data logging.