Hardware Phones:

Nortel 1535 - Style and cheap H.264 SIP VOIP and Video Phone
TANDBERG E20 - SIP VOIP and Video Phone
8x8 - SIP Broadband Videophone
ATL IP400 SIP Videophone (Seen working with a GXV3000)
AuPix - SIP & H.323 Videophone with Browser
Grandstream GXV3000 - Cheap H.264 SIP Videophone
Grandstream GXV3005 - Updated version of Grandstream GXV3000
Grandstream GXV3140 IP Multimedia Phone
Grandstream GXV3175 IP Videophone - Voice and/or video H.264/H.263/H.263+ and embedded Skype, browsing etc too.
InnoTele - Broadband SIP/H323/3G videophones for IP video telephony with WiFi
InnoMedia - MTA 3368 IP VideoPhone
Leadtek Research Inc. - Cheap H.264 Videophone/SIP IP-Camera
Ojo - SIP Broadband H.264 Videophone (formerly branded/distributed by Motorola)
WookSung Elec. - SIP Broadband Videophone, Web Videophone.

Software Phones

AuPix - SIP Voice, Video and Real-time-text Videphone Software for PC, Android, etc
Ekiga - Free SIP Audio/Video phone
WengoPhone - Videophone from Wengo
TABLETmedia iFon - soft videophone for PDAs and Smartphones
Kapanga - Free VideoPhone
Video Processing - VOIP video processing technologies and mobile programming.
X-Lite - free soft videophone
eyeBeam - eyeBeam softphone
Bria - newest softphone from CounterPath
Intellivic Softphone - Intellivic Softphone
Intellivic Softphone Demo - free Intellivic softphone demo
Mercuro IMS Client - Free IMS/SIP videoPhone
http://videospindoor.netspin.it - SIP Video IP door softphone
http://www.jitsi.org/ - Previously Sip-Communicator - Voice and Video - h264 capable

Dead Projects

Viseon - VisiFone SIP compatible Video Phone (site is dead 2009.02.09. Company out of business)
Pic-tel videophones - SIP or h323 videophones for IP video telephony (site is dead / 2007.06.02)
Call Image Videotel - SIP Broadband Videophone / VideoStreaming / Web browser (site is dead / 2007.06.02) Company is out of business :(

Videostream only

Videostream on Snom 370 - An implementation for Snom 370 Phones, which uses the build in minibrowser (german only)

Where to Buy

America - Video Phones from .e4
America - Video Conferencing Equipment from VoIP Supply. Get the Grandstream GXV3000 here!7
Belgium - VoIPandGo.be Quick delivery by UPS. Reseller Prices Available!!
Venezuela - FONLOGIC Grandstream GXV3140 and Grandstream GXV3175 Multimedia Video Phones