The Uno for Arduino:
It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button and features the Atmega8U2 programmed as a USB-to-serial converter and has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.
The Sensor Shield V4.0 for Arduino:
It allows you to connect to various modules like sensors, servos, relays, buttons, potentiometers.
The LCD Keypad Shield for Arduino:
It includes a 16x2 HD44780 White on Blue LCD module and a 5 push button keypad for menu selection and user interface programming. Fully assembled. On-line Arduino tutorial and example code. Compatible with Arduino Uno, Mega, Duemilanove. Uses digital pins 4 - 10, and analog pin 0.
The XBee board for Arduino:
It allows to wireless communicate over a modified ZigBee protocol using the popular XBee module from Maxstream.
The Ethernet Shield for Arduino:
It is based on the Wiznet W5100 ethernet chip. The Wiznet W5100 provides a network (IP) stack capable of both TCP and UDP. It supports up to four simultaneous socket connections. Use the Ethernet library to write sketches which connect to the internet using the shield.
1 Uno Board
1 Sensor Shield V4.0
1 LCD Keypad shield
1 XBee Shield
1 Ethernet Shield