OCD is an account that supports good content on Hive. The letters stand for Original Content Decentralised. It was a move to support and encourage good content creators and discourage posters who behaved in ways that brought Hive into disrepute.

OCD has had several initiatives to help grow Hive. The latest one is the Communities Incubation Programme which supports communities like The Ink Well by voting for good posts submitted by the community curation team. OCD also delegates to the community, increasing @theinkwell's voting power, and supports the people who co-ordinate the community by rewards on @theinkwell's posts.

HBI is another initiative to help distribute wealth to more people on Hive. By buying an HBI share and sponsoring another account, both accounts will receive upvotes on their posts. It is a mutual initiative where people on Hive support each other and help Hive to grow. The link in @josephsavage's comment will give you more detail.