2002: As noted elsewhere today, I’ve been using ramBunctious, a classic Mac OS RAM Disk program, for years. Although it works in Classic Mode under Mac OS X, the RAM disks it creates are inaccessible to OS X, so I’ve retired a real workhorse program.
2001: The newest addition to our benchmark suite is TimeDrive 1.3 (available here), which measures drive throughput. This can test a floppy, Zip, hard drive, or RAM Disk. TimeDrive is fairly primitive; the benefit of that is being able to run it on very old Macs.