As we use RouterOS a lot in our company (ABCom Albania), to offer our clients the best of our services, and while we have a lot of Mikrotik routers around, and all the hosts are saved in the host list of Winbox, it would be a great feature to be able to search through all the IP/MAC addresses for a given IP/MAC in the list.
thanks, this is planned in a future upgrade of Winbox loader. Currently, I can suggest you to use the Dude for managing large networks of RouterOS devices: http://www.mikrotik.com/thedude.php