Brain Games - Boost memory power with free brain games
aerelight Desk Lamp - A simple, sleek OLED lamp
Dualnback.works - Dual N-back is a specific brain training exercise, that's been shown by research - it might improve fluid intelligence.
Finmark - Financial planning software for startups
Pixelogic - Daily Picross - Nonogram logic game with 5000+ puzzles and a daily puzzle
Pry Financials - Finance for Founders