All This Useless Knowledge

Via David Pogue: Obsolete Technical Skils. It's a wiki, so some of them are not technical, not obsolere, or not really skills. But the "U" section is terrific:

Using a Typewriter
Using a card catalog
Using a 16 mm film projector
Using a fountain pen
Using a slide rule
Using a beeper or pager
Using an abacus
Using carbon paper to make copies
Using correction fluid
Using a fax machine
Using a flash bulb
Using a flash cube
Using a Timing Light