LibVNCServer/LibVNCClient are cross-platform C libraries
Linkedin Automation Tool
High-speed, 3D-friendly, TightVNC-compatible remote desktop software
3D Without Boundaries
Backup and Recovery Made Easy
mRemoteNG is the next generation of mRemote, open source
HTML5 Clientless Remote Desktop
XDM-OPTIONS Display Manager Suite
Various multi-platforms projects coded in FreePascal/Lazarus or Qt C++
The GTK Remote Desktop Client
an extremely buggy web app !
Twin is a "retro" program for embedded or remote systems