Nuclear Chess: Chess variant with AI, playable in the browser
Do Again List: A self sorting list of things you want to do somewhat regularly
Lots of games, some cross-platform games and some games for the obsolete Sharp Zaurus and Agenda VR3 mobile devices.
SFont, a very simple font library supporting fancy bitmap fonts (with colors and alpha channel) and basic kerning. Has been successfully used in dozens of projects by other people.
Experiments
Litespread: Adding a basic spreadsheet UI to SQLite, also nice for handling CSVs
iprefer.to: Rating site that uses comparisons instead of star ratings