Want a good example? StarCraft64 on the N64 (PC too actually, but different circumstances).
Instead of storing string names it generates 32bit hashes. That means that file lookup only requires you to take the original string, convert it into a hash, then search for 32bit values instead of using something like strncmp a billion times. With 2850-some-odd files, that matters a lot.
Another really handy side effect is that instead of having to compare data of various sides all your hashes are the same length, and when doing standard int comparisons it takes more code to grab individual entries than comparing the values. It's radically faster.
To be fair though, they use a lousy implementation of it ;*)
Certain modern PC games will generate a hash based on a filename and use it as a decryption key. Unless they have a filelist, you'd basically have to brute-force files out of them--something that could take, no joke, millions of years in the worst case.