The ATtiny85 module is a great option for running simple Arduino programs, it's small, cheap and relatively easy to use. If your project requires only a few simple inputs or outputs, then this is ideal module.
Features:

1. support for the Arduino® IDE
2. power via ubs or external Source (pinheader)
3. onboard 5 V regulator
4. built-in usb
5. 6 I/O pins
6. 8k flash memory (about 6k after bootloader)
7. I2C and SPI
8. PWM on 3 pins
9. ADC on 4 pins
10. power LED and LED on P1

Specifications:

1. working voltage: 1.8 - 5.5 VDC
2. dimensions: 17.5 x 19 mm

vma108_a4v01.pdf

atmel2586_datasheet.pdf

vma108_scheme.pdf

vma108_example.zip

vma108_digistumpdrivers.zip

ce_rohs_open.pdf