Cryptography, UUIDs and some other hashing things, certain kinds of counters. Also, 2^64 is only about 10^19, so if you happen to have 20 exabytes that you wan

Cryptography, UUIDs and some other hashing things, certain kinds of counters. Also, 2^64 is only about 10^19, so if you happen to have 20 exabytes that you want to byte-address, you can't do it with 64-bit pointers.