1. Home automation system using Arduino or Raspberry Pi
2. IoT-based weather monitoring station with data logging
3. Digital thermometer with LCD display
4. Bluetooth-controlled robot or car
5. RFID-based access control system
6. GPS-based vehicle tracking system
7. Wireless weather station using sensors and microcontrollers
8. Electronic voting machine with security features
9. Digital audio player with equalizer
10. Smart wearable device for health monitoring
11. Electronic dice using microcontrollers
12. Digital clock with alarm using RTC module
13. Gesture-controlled robot or device
14. Voice-controlled home automation system
15. Arduino-based obstacle avoidance robot
16. Wireless communication between two Arduino boards
17. Home security system with intruder detection
18. IoT-based smart irrigation system
19. Digital voltmeter and ammeter using microcontrollers
20. Wireless doorbell system with camera
21. Arduino-based temperature and humidity monitoring system
22. IoT-based smart energy meter with billing features
23. Biometric attendance system using fingerprint sensor
24. Bluetooth-based chatting application between mobile devices
25. IoT-based smart parking system