Yesterday, Amyas let his tea get cold on his desk. I mentioned that a USB cup warmer would stop this happening; Amyas, being a sensible chap, seemed surprised that such a thing existed. Well, I knew I'd seen them somewhere, and I thought I might purchase one for fun. I looked on the internet... and there were USB cup warmers . Great. But it isn't that simple. You can pay anything from £2 to £20, it seems, for a single warmer. You can choose between silver, white, black, gold, all in different shapes and sizes. You can get a USB cup warmer with integrated 4-port USB hub. Some cup warmers come with cups. Or stainless steel cups with lids. Some are flat-topped, some have round indents, some have on-off switches and LEDs. Some - very rare, this kind - have LCD clocks and temperature readouts! Some offer 50-60C warming; some 40C to 80C, from outer edge to centre. I'm overwhelmed by the variety! I am awed that so many people should have designed these gizmos and had them manufa...