There are many web conferencing services out there, but I've found some of them cumbersome to use, especially when I need to rapidly connect with someone. Google+ Hangouts can get the job done quickly and reliably - and, best of all, it can do it for free. Note: you can add a maximum of 10 people to each Hangout.
What you will need
- A Google account (not required for the other participants)
- A computer, tablet or smartphone with Internet access
- A webcam with a microphone, speakers/headphones, and the Google video chat plug-in to use audio/video conferencing services (if applicable)