The Arduino Mini is a miniaturized version of the Arduino board (without the USB port). This board comes fully assembled with pins, and an ATMega328 preloaded with the Arduino bootloader.
Minimal dimensions (30x18mm) allow space saving.
It use an ATMEGA168 with 16K of program space and it is usable with USB/Serial converter for programming and to add the USB port.
0-A000003Arduino Mini Main Page Free Open-Source IDE