Arkham just launched Arkham username. Sign up. Go to the settings and claim username.

https://platform.arkhamintelligence.com/signup?referrer=ZTBkY2M0YTQ0MzI3NzI4Yjg0Mjc0MDFjZWNkZDUwMDhiZDU4NDAwNTY2NTRkN2JmNWExZTljOGZkNTE0NGNlOGNkOWMzNWUzMzQ0OGY0MjczYTg4ZWY5MWFiYjEzNQ