I have written a patch that makes possible searching objects on maps. It searches by map object labels, network host's name, IP and DNS, trigger description, host group name. The found object is highlighted with yellow marks on the network map.
The patch is quite dirty, it uses SQL statements for searching, and should be rewritten to use Zabbix API. Not tested with distributed monitoring, and will possibly fail.
Detailed description, screens and patch:http://www.zabbix.com/forum/showthread.php?t=19513
Please add this functionality to the mainline Zabbix code.