yahoo chatrooms have that option. i not sure how they script it but a easier way to do it would be flash but as far as the microphone and people in a chat its hard to keep that under control cause you always got someone who wants to be a ass.. and will just keep whoring the mic and either saying stupid stuff or just playing music through it all day which will mean others cant talk. the only way a mic is good is with private rooms usually. and if ya want a chat with a mic check out the plugin section theres a flash chat that is hosted by them and it allows video and mic through flash
https://vborg.vbsupport.ru/showthread.php?t=93539