We found this Arduino AVR ISP programmer particularly interesting. AVR microcontrollers can utilize an interface called In-System-Programming. ISP allows the chip to be programmed or reprogrammed ...

Like the people in and surrounding Raspberry Pi, clever souls in and clustered around Arduino have done all sorts of things, including worked out ways for one Arduino to programme another Arduino – ...

This fully compatible alternative to the Arduino bootloader requires an AVR ISP programmer to burn it to the chip on your Arduino.