http://sourceforge.net/projects/scdp/

This software send out cisco discovery protocol (CDP) packets. Cisco AP's (maybe others too) shows then much more information about wireless clients, including [host]name for example. Requires libnet.

CDP decoder can be obtained from here http://sourceforge.net/projects/lcdpd/. This is kernel patch, allow to read decoded CDP packets via /proc/net. I tested it and after some modification, this patch can be used with openwrt. Dealing with many wireless clients can be much easyer, if you can see also client names together with mac or ip addresses.