Although NiceHash is usually regarded as a mining service, it's better to say that it's a kind of a platform for selling/buying cloud mining contracts. What is special about NiceHash is that users can opt for both selling and buying the hash power on this platform.
CKPool also known as Kano Pool is a BTC mining pool with a 0.9% fee and shared transaction fee rewards. The pool doesn't require registration for basic use but includes indepth stats for registered miners. The pool and pool software were created and are run by the CGMiner developers.