Rainglow Color Themes - 320+ color themes for a variety of editors and software.
globalquiz.org - Difficult, multiplayer and multi-language trivia game.
Slack Themes - Make your Slack pretty with custom themes
HugeQuiz - test your knowledge with a variety of quizzes about everything.
eM Client - eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.
ActionQuiz - ActionQuiz is an online website that lets you select a quiz and play against computer opponents to see which one of you is smarter.