/list #channel
sometimes channels put the key in the topic just to prevent bots.
failing that, msg an op
if its a registered channel on a network with services(chanserv etc) try /chanserv info #channelname to get the name of the creator(owner) of the channel. that person might be online but not in a /names result. /whois ownernick to see if they are online and if so, /msg them for the key.
btk
