Palbee is a free online service which allows you to set up easy video meetings with your friends and colleagues.
You can also use Palbee to record your own presentations and store them online.
Site lets teachers post a question online. Students then respond via webcam (no account required) and have their (moderated) comment added to a really great-looking video wall online. Site does cost $65 annually, but that includes 10 walls and virtually endless questions/responses.