Using Skype you can easily display a guest speaker to a class via a large monitor or projector and then have the group/class ask them questions. Depending on the class & available facilities you may want to have a "middle man" that puts the questions to the guest speaker either via microphone or text based chat.
"Skype in the classroom is a free global community that invites teachers to collaborate on classroom projects where they might use Skype, and share skills and inspiration around specific teaching needs."
If you want to record the audio from a Skype conference as an MP3 for later listening you can do that by using either MP3 my MP3* or Skype Call Recorder you can learn more about each of them by clicking on the links above.
You can also record and edit video chats using Vodburner.
Access Skype without admin rights
If you ever need to access Skype on a machine which you can't install the Skype software to then you have two options:
Printable guide: Skype in the classroom