Contacts

You don’t need to say Yes or No when someone wants to add you as a friend; you can simply ignore it, the request will go away. (On the other hand, someone with whom you chat often will automatically turn to be your friend, unless you disable this).
The Gmail account 'user@gmail.com' can't be invited as your friend.
Sound & Video

It's possible to broadcast music, MP3, etc.. through Google Talk.
Unplug your microphone. Double click on the speaker icon in the lower right corner. This will open
up "Volume Control". Select "Options" and then "Properties". Then check the button
next to "Recording" then click OK. You may also have to change your setting under
Mixer Device. Now the Recording Control screen should be up. On my computer I selected "Wave Out Mix". Click on the green phone in Google Talk and call your friend.