Amanduino is a clone of popular Arduino platform. It has 30kB for user program, 2kB RAM and 1kB EEPROM, 14 digital input/output pins (1 UART, 6 PWM ports) and 6 analog inputs, built-in Real Time Clock. It's really small just 5.4x5.4 cm (2.1x2.1"). Amanduino is breadboard ready and Arduino shields compatible.