Prior to NVIDIA porting CoolBits over to Linux back in 2005, the only way to overclock your NVIDIA graphics card was using NVClock. NVClock has been developed as a third-party open-source utility by Roderick Colenbrander and hosted at SourceForge and LinuxHardware.org.
NVClock is not dead. I update it slowly. The reason that there is no Beta3 yet is that I want to offer some reasonable Geforce8 support but as I lack Geforce8 hardware I can't do much. The Geforce8 is a very different GPU. Most of my time is spent on Wine at the moment.