TurboVNC
High-speed, 3D-friendly, TightVNC-compatible remote desktop software
... and libvncserver, and TurboVNC is also compatible with any other TightVNC derivative.
TurboVNC forked from TightVNC in 2004 and still covers all of the TightVNC 1.3.x features, but TurboVNC contains numerous feature enhancements and bug fixes relative to TightVNC, and it compresses 3D and video workloads much better than TightVNC while using generally only 5-20% of the CPU time of the latter. Using non-default settings, TurboVNC can also be made to compress 2D workloads as "tightly" as TightVNC.