This USB Cable converts from a USB connection to an RS-232 TTL connection. Use this cable for programming Arduino boards that do not have a built-in USB connection.
This USB board converts a USB connection into a RS-232 5V serial connection. Use this for Arduino and related boards that do not have a built in USB chip. Based on FT232RL chip from FTDI.
This Wiznet 811MJ Ethernet module makes embedding internet functionality into your project easy. Plugs into compatible Ethernet adapter shield or the iTelegraph kit.