RiaPlot is little program that can interpret data from a gamma counter measuring test tubes marked with radioactive elements, in order to calculate the concentration of a solution.
Counts are taken from test tubes of known concentration, and controls, a standard curve of concentration vs. radioactivity is produced. This can be compared with unknown samples. Although the calculations necessary would be extremely tedious to carry out by hand, no great processing power is required. RiaPlot is quite happy to run on an old LC connected to a gamma counter.
You can download RiaPlot version 1.7b. The file contains a program that will run on both 68k and PPC Macs. Slim versions are available for the asking.