Here is another educational robot compatible with Arduino. The Pololu 3pi+ 32U4 OLED Robot is based on the ATmega32U4 MCU. It comes with line sensors, front bump sensors, 9-axis IMU, and a graphical OLED display.
The 3pi+ comes with two H-bridge motor drivers. It has a 128×64 graphical OLED display, buzzer, and indicator LEDs. It has a wrap-around bumper to protect the electronics.