OK, so it may be slightly less than 100 ways, but this article provides a wide variety of assays to measure cortisol levels. It also provides great background on the hormone itself. This article also tells how precise an assay could be, what the environmental impacts are, and most importantly, what everyone else is doing.
For my proposal, the differences in the measurement abilities of different tests are significant due to the fact that I’m measuring both salivary and serum cortisol levels.
Kirschbaum, C., & Hellhammer, D. H. (1994). Salivary cortisol in psychoneuroendocrine research: recent developments and applications.Psychoneuroendocrinology, 19(4), 313-333.