Teleseminars for Teaching
For Tele-Conferences many well informed lecturers are using the free service at FreeConference.com. Your call-in guests will have to pay the long distance charges, but there is no additional charge for the call itself.
However, you will want the service to make a recording. It is available, for $9 per month. The service outputs an MP3 file that can be downloaded within 30 days after the recording. A CD made from this MP3 would be an appropriate gift to mail to the participants.
When you make some visuals available from your website, for example as a pdf file, this will increase the learning accomplished. You can just create the pdf file, with words and pictures, from Microsoft Word or Powerpoint, and upload the file to your website. Then, during the call, tell the listeners to point their web browser to www.yoursite.com/picturesforthetalk.pdf.