The GPC Group's four current benchmarks -- the Picture-Level Benchmark (PLB), Xmark93 Viewperf and GLperf -- are all available to the public through anonymous ftp.
The PLB benchmark (a sample implementation that runs under PEXlib; versions that have been customized for a variety of computer vendors and graphics libraries are available by contacting the PLB member companies listed on the Member Page.), the Benchmark Interface Format (BIF) specification, eight standard benchmark files, and files to test PLB implementations are available in the PLB directory.
The XPC directory includes the script and documentation for Xmark93.
The Viewperf source code and the three current viewsets are available under the OPC/Viewperf directory.
Here are the instructions for obtaining the benchmarks: