Cheese is a Photobooth-inspired GNOME application for taking pictures and videos from a webcam. It also includes fancy graphical effects based on the gstreamer-backend.
Ekiga (formely known as GnomeMeeting) is an open source VoIP and video conferencing application for GNOME. Ekiga uses both the H.323 and SIP protocols. It supports many audio and video codecs, and is interoperable with other SIP compliant software and also with Microsoft NetMeeting.