In these days of mark-up languages believing they have made spreadsheets old-hat, I often point out that spreadsheets are a mark-up language, that they were invented by the ancient Egyptians and they still have a long life ahead of them. In fact it seems they were invented by Mesopotamian accountants before being taken across the Red Sea to Egypt.
Of course in these days where the latest mark-up language is “the best sliced bread” since the previous mark-up language, I saw a very interesting slide at a conference late last year that showed how clearly spreadsheet cells map to RDF OWL Triples. (A slide Kari Anne borrowed from Thore I understand.)
[Post-Note: Followed up this thought and the Thore Langeland “triples” reference in a paper on by business site. “For the Love of Spreadsheets”.]