The Sparkfun Arduino protoshield as some very useful portable prototyping space that plugs onto the top of the popular Arduino / Freeduino SB.
The ScrewShield is a “wing-format” shield that extends the Arduino pins to sturdy, secure, and dependable screw terminal blocks. (You even get a few bonus terminals for extra GND and power!&#
The Ground / Voltage / Signal standard is very popular, and our SB-GVS shield lets you easily tap these sensors into your Arduino!
Looking for the smallest Atmel microcontroller with built-on motor drivers? The BittyBot MEGABitty microcontroller features an Atmel ATMega8L, motor drivers, and voltage regulation in tidy 0.9" x 0.9" package!
This is a handy AVR programming cable that incorporates both the 10-pin and 6-pin ISP programming interfaces.
Just need to make some motors move with your Arduino? Here's a simple way from SparkFun - the Ardumoto!