Look into mushroom identification - many little brown mushrooms (LBMs) are differentiated only by careful microscopic analysis of their spores or DNA sequencing. Mushrooms are especially difficult because many of the potentially useful identifying features are only present at certain (short - hours or a day or two) phases of the lifecycle of the fruiting body.
Finally, for those who think genomic/genetic studies are being used inappropriately, consider that while they may seem to me to be, in practice, just another sort of 'data processing' (which they are not - they are often just generalised (or even generalized), and their application to new contexts is not that different to simply applying similar analysis to previous contexts) it is possible, for example, that, for example, the study of the DNA sequences of fungi actually (if you want to make a broader and very broad claim about fungus genomics) might in the future yield, in this particular case, a much more detailed, more reliable (and possibly more objective) classification (if not entirely a direct one) of some of the fungi and their eukaryotes in our immediate neighbourhood.
I've also got to say that for the same reason, I don't have a lot of confidence in the 'fungal genomic analysis' thing in particular, because, on the whole, it seems to me to be so easily manipulated.
