This is a simple to use USB AVR programmer. It is low cost, easy to use, works great with AVRDude, and is tested under Windows, Linux, and MacOS X.
Put your Ardweeny onto a prototyping shield, and add regular shields to it!
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!
The Adafruit Motor/Stepper/Servo Shield gives you excellent flexibility in ways to create motion with your Freeduino SB or Arduino microcontroller!
This Adafruit GPS shield turns your Arduino into a GPS location datalogger! (GPS & SDCard not included)
The HV Rescue Shield 2 is a high voltage parallel mode fuse programmer for Atmel AVR microcontrollers.
Want a tidy AVR-ISP compatible programmer that also acts as a USB to TTL converter? Pololu's Orangutan USB AVR programmer fits the bill!
The LoL Shield is a build-it-yourself kit that creates a charlieplexed LED matrix for the Arduino
The assembled PWM shield will fit on any board that is pin compatible with an Arduino and will give you control over 32 PWM channels instead of the standard 6 on the Arduino Uno.