I think it's interesting that this has been quite a slow thread - it's hard to think of categories of tools that are no longer made at all. In that respect, woodworkers are better off than, say, photographers. Good luck to you if you want to explore film-based photography without the infrastructure of film makers, chemical suppliers and anyone making equipment to use in developing and printing. Wood is still plentiful, and can be cut by hand in just the same ways as it was a century ago, or a millenium.
However, there is one category I'd put on the 'red list' of endangered species - files.
Eric noted the rare Abrafile as having gone, but the problem is wider than that.
Files are really ancient tools. Millions upon millions were made, by hand, following a laborious sequence of heatings, hand cutting with hammer and chisel, tempering, straightening etc. Throughout the early industrial revolution, they provided the common way to shape iron, until the rise of the machine tool and its rotary cutters in the later part of the nineteenth century.
But to a woodworker, files are important because they make saws possible. There's no need to repeat all the content of the testing work done on saw files in Australia - you can read it here -
petition-for-quality-saw-files-t71552.html - but to summarise:
Pretty much all production of files has ceased in USA and Europe; what is available from cheaper manufacturing areas may look like files and bear a familar name, but lack essential, functional details that used to be universal.
Worldwide, major trades which used to use files by the boatload - metalworking, shoemaking, clockmaking - have switched to quicker methods for bulk production.
So if you want to use old saws and keep them sharp, buy all the good old saw files you can find. And if you want to do small scale metalwork by hand, stock up with good old files of any shape you might need.
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