- cli ncurses calendar
- x86 assembler
- binary translator - x86 to arm
- java bytecode to asm
- some esolang
- arm emulator/interpreter
- quake x metroid game
- posix-compliant os
- rsa cryptography
- roll-your-own crypto library (for fun)
- write a tiling window manager
- json parser - just something easy and refreshing :-)
- rendering fonts from scratch
- raytracer in a weekend
- x graphics programming
- sdl + alsa music player