This document outlines various revenue opportunities for public transit systems like Delhi Metro from leveraging existing infrastructure and digital platforms. It suggests generating income from music kiosks, mobile apps, WiFi access points, food courts, self-ticketing kiosks, TV screens, gaming kiosks and renting out retail space. It also discusses branding opportunities through ads on walls, doors, escalators and inside trains. Revenue can be earned from embedded mobile ads, integrated bus schedules, train alerts and pay-per-use services like recharging through the metro system.