This isn't about books, but I love the word so I thought I'd copy this curiosity over from my other blog. The Gömböc (pronounced "gəmbəts") is an intriguing object devised by Hungarian mathematicians Gábor Domokos and Péter Várkonyi, that has the property of self-righting to a single stable position despite being homogeneous, completely convex and not being obviously "flat" or "thin". (That is, this self-righting property is easy to obtain if you allow internal hollows or heavy inserts that skew the weight distribution, as in the Weebles or Balancing Ovoid toys - but it's very difficult to achieve if the object doesn't curve inward, and is solid and the same material all the way through). More on this at the Mathematical Intelligencer article Mono-monostatic bodies: the answer to Arnold's question (PDF).
As with many other shapes with useful mechanical properties, this self-righting behaviour has already been achieved in nature in animals such as the Indian Star Tortoise. See The Living Gömböc (Adam Summers, Natural History Magazine, March 2009) - which rather debunks the scenario presented to Leon at the beginning of Blade Runner. High-domed tortoises self-right, and flatter ones use their limbs.
Compare the rattleback or celt, an object of no discernable application, but one also with unusual dynamic properties: in its case, a preferred direction of spin.
Gömböc is, incidentally, Hungarian for fatty or rotund, or a pork haggis, like the sinister one in the Hungarian folktale A kis gömböc that hangs in a cottage attic and eats a family. Would you believe, there's even a Gömböc Festival in the Hungarian village of Kömörő. A related word, gombóc (pronounced "gombawts", approximately) means dumpling (Serbian equivalent gomboce, I've just been kindly informed). "Gombóc" is also a Hungarian nickname for cute plump little animals: a great many such pictures have the caption "Gombóc Artúr" (Dumpling Arthur), who is a chocolate-obsessed overweight cartoon bird.
Addendum, 1 June 2009. Small world: at a bus stop at Exmouth today, I was sitting next to a family of unknown nationality but evidently Eastern European; and the one word that stood out in their conversation sounded like "gombosh". They were eating jam doughnuts, which explains it.