1. LED Matrix Animation
   Program an LED matrix to display scrolling text or animations using the ATtiny85.

2. Miniature Digital Thermometer
   Build a small thermometer using a temperature sensor like LM35 or DS18B20 and display the data on a tiny OLED screen.

3. IR Remote Control System
   Decode signals from an IR remote to control LEDs, fans, or other appliances.

4. Sound Reactive Lights
   Create an audio visualizer where LEDs blink in response to sound or music using a microphone module.

5. Capacitive Touch Switch
   Make a touch-sensitive button using a conductive surface and the ATtiny85, perfect for smart home switches.

6. Portable Motion Detector
   Use a PIR sensor to build a portable motion detection alarm system for security purposes.

7. USB Volume Controller
   Turn your ATtiny85 into a USB HID device to control your computer’s volume with a rotary encoder.

8. Tiny Weather Station
   Measure temperature and humidity with sensors like DHT11/DHT22 and display the readings on an OLED.

9. Ultrasonic Distance Meter
   Use an ultrasonic sensor to measure distances and display them on a small display.

10. Blinking Bicycle Light
    Create a small, energy-efficient blinking tail light for a bicycle, powered by a coin cell battery.

11. Minimalist USB Game Controller
    Build a simple game controller for retro-style games with buttons connected to the ATtiny85.

12. PWM Fan Speed Controller
    Control the speed of a DC fan using pulse-width modulation and a temperature sensor for feedback.

13. ATtiny85 Robot Brain
    Power a small robot with an ATtiny85, controlling motors and sensors for basic navigation.

14. Night Light with Light Sensor
    Create an automatic night light that turns on in low-light conditions using an LDR and LEDs.

15. Tiny Digital Stopwatch
    Design a simple stopwatch with start, stop, and reset functions using push buttons and an OLED display.

These projects highlight the versatility of the ATtiny85 and can help you learn more about electronics, programming, and sensors. 

This site is hands down the best for projects related to ATtiny85. So, definitely check it out.