While answering another question I used the English word furlong which is obsolete in usage, at least in the UK, except for in horse racing. This set me thinking about Spanish usage. For instance I remember colleagues referring to different sizes of floppy discs using the term pulgada but that I suppose is really because they were originally named in inches in English and converting to an exact number of millimetres would have been absurd.
There is a long list of candidates in the Spanish edition of Wikipedia here. Are any of these still in popular use? I think we should probably exclude any which are only used in a stock phrase like the English phrase "To hide one's light under a bushel"
It would be best if there is an example of a whole area of application which has clung to the old system like the example of horse racing in the UK which still uses the old terms for both weight and length.