iChat http://www.apple.com/macosx/what-is-macosx/ichat.html
If you have a Mac, iChat is a great option. Included with Mac OS X, iChat is an instant messaging application that works with your AIM or MobileMe account that makes it easy to stay in touch with friends and family using text and video. The service offers excellent voice quality, razor-sharp videoconferencing with three others or audioconferencing with nine. Its also less of a bandwidth hog than Skype.

ooVoo http://www.oovoo.com/
To use ooVoo, all you need is broadband internet access and a computer with a webcam and microphone. The service is free for video chats with up to 6 people at once. ooVoo easily imports your contacts from your IM services, social networks and email address book. It allows you to record and send video messages and audio and video calls. You can chat in full screen mode and text, chat and share files instantly while on a call. Even if the people you want to call dont have ooVoo, you can have a free browser-based online vchat with them by sending a Web Video Call link