The web is full of cool things. Here are some:
Browser based
- asciiflow.com - Lets you draw flow charts and write down thoughts in ascii. Source
Command Line
- TextQL - Execut SQL commands against CSV/TSV files
- wish - make SSH apps
- bubbletea - TUI framework
- pico.sh - ssh based services like website hosting
Electronics
- The Megaprocessor - Walk-in microprocessor.