Colaba Causeway. Sev puri, dahi puri 12/-, pani puri 10/-, ragda patties 8/- [9/95].
Yet another old favourite, Kailash Parbat is never empty. There is a proper sit-down restaurant somewhere beyond the crowd, but the real stuff is what you can eat standing up.
This is certainly the most popular place for snacks south of Chowpatty. The sev puri and dahi puri are recommended. The pani puris are harder to judge. Every person has his favourite street corner where the most delicious pani puris in the world are sold from a cart. Nevertheless, I do recommend them here, specially since I've never been laid low after gorging on them.
Bombay snacks: Dwarka Kailash Parbat Samovar