Updating User Profile on Registration

Try dumping your data and you should see the problem:

function coinDeposit() {
  $current_user   = wp_get_current_user();

  var_dump($current_user); die;
  update_user_meta( $ID, 'depositAddress', $account);

}

The user object is empty. That is because a newly created user is not automatically logged in. There is an email confirmation step, and then login. Until that login, wp_current_user() isn’t going to give you a user object.

Fortunately, user_register is passed the user ID by the Core. Just use that:

function coinDeposit($ID) {
  $coin       =   new jsonRPCClient('http://user:[email protected]:14022/');
  $account    =   $coin->getaccountaddress($ID);
  update_user_meta( $ID, 'depositAddress', $account);
}

add_action('user_register', 'coinDeposit');