Even though I have mentioned these under specific languages, you can make anything in any language of your choice.
- Bootloader
- Task scheduler
- Your own UNIX like short commands
- Your personal website using Flask
- Attendance register
- File Explorer
- Image Viewer
- Imgur Clone (file upload, saving files, return files to user)
- TitanPad Clone (TCP or UDP sockets)
- Event management website
- Local place discovery website
- Messaging Queue
- P2P file sharing via HTTPS, WebSockets
- Setting up a QUIC client and Server
- Wikipedia clone
- News portal / Blog
- Notes taking app
- URL Shortener
- Soundcloud Clone
- Live ticketing website using sockets
- Games ( Love2D, Solar SDK )
- GUI utility widgets using LuaIUP
- Operating System (Virtual)
- Make images using mathematical formulas
- Image editor
- Gradient Generator
- Image editor using canvas
- Browser Extensions
- Google Input Tools OFFLINE replacement
- Visualize classes / functions as a map or 3D space
- WebRTC/HLS/RTMP based live streaming website