The entire set of Scientific American's "The Amateur Scientist" columns, every single column, from 1928 to 2001 (when the column ended), text and figures, scanned and searchable, on a CD-ROM.
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These guys are good guys too--I've been getting their e-mail specials for years.
This CDROM is so good I nearly bought another copy, even though I already have two (check that--maybe three!).
Also includes selections from John Strong's classic, "Procedures in Experimental Physics," optics, glass-blowing, telescopes, and other resources of the highest caliber.
You will not find a finer reference.
A great stocking stuffer for a budding scientist, too.
Cheers, James Arthur