Conflab.com: Service enabling internet conferencing for voice, video, and data calls.
Paltalk: Operates with different chat systems such as ICQ and AIM, and enables live video calls. [Windows]
SharpVoice: Free PC-to-PC and paid PC-to-telephone calls. Windows 95/98/NT/2000/XP supported.
SipTelecom: Free Internet Phone Numbers (iPN) allows you to get video conferencing calls from your web site and email messages.
Skype: Peer to peer internet voice service. Mac, Windows and Linux versions available. Users may call landlines and cellphones for a fee; users may call each other for free.
Visitalk.com: Free calls and chat anywhere in the world with NetMeeting or CU-SeeMe. Includes voice and video support.
Vitez Multimedia Solutions: Maker of PicoPhone, an Internet phone application with chat.
VocalTec: Providers of integrated communication solutions, including software to allow web-page visitors to call any telephone from their multimedia PC. A useful solution for customer support.
WebPhone: Use WebPhone software to call any phone, including mobile phones.
World Voice Cafe: Offers free voice chat with text and sound communications available.