Keccak uses a sponge function which is cool but what benefits does keccak have over sha-256 for cryptography operations in the code? thanks
While Monero does not use Keccak for its hashing, one advantage of using CryptoNote is to prevent Monero from immediately being able to be mined by ASICs. There is tremendous investment in SHA-256 hashing because of Bitcoin's popularity, so using a less popular / more memory intensive standard allows Monero to be mined by the "common man"- at least until ASICs are developed.
Keccak has "built-in" protection against length extension attacks.