SpiderBoard 1.1 is an atmega 168v-10-AU low voltage breakout board. Designed to be a minimalist and simple board, the pinout matches that of the chip 1:1.

The only added discrete components are a 16Mhz oscillator (which you can disable to get two more pins) and enough circuitry in the form of a resistor and a capacitor to keep the chip out of reset. You can also choose to disable that as well by desoldering the two components and then disabling the RESET programmable fuse.

This is, in essence, the simplest possible Arduino-compatible board. Full instructions are given on how to configure the Arduino IDE to use this, and the optiboot v8 bootloader is pre-loaded onto the chip for you. By default it uses only the onboard oscillator (8Mhz) and can be re-flashed using an Arduino ISP or usbasp to be configured to use the external one.