It would be very nice if there were a way to tell the mongo server to initialize a replica set automatically after starting up. For automated sysadmin setups (like Chef), it can be very difficult to fully bootstrap several mongo nodes for a replica set. This is due to the fact that you have to wait for the server to come up, then call rs.initialize() in the shell. If there were some way via the CLI options (and config file) to instruct the server to do this automatically, it would make automated bootstrapping much, much easier.