Instead of making perfectly round coins, make them slightly oval shaped, so that when they are dropped, they can't roll away too far.
Call them Keplers in recognition of the great physicist's work on the laws of planetery motion; print his head on one side, then run some mathematical detail about each different planet's particular orbit along the respective coin's edge.
[I just lost two Euros under the fridge ;-( ]-- xenzag, Jan 27 2009 if you've never seen one http://en.wikipedia...ralian_50_cent_coin [simonj, Jan 28 2009] Gömböc http://de.wikipedia...ki/G%C3%B6mb%C3%B6cUnwieldy yet possibly fun to wield in a sock [loonquawl, Jan 29 2009] I think somebody ought to suggest (maybe in an annotation) a retrofitted skirt for fridges to eliminate the problem of things getting lost underneath them.-- MaxwellBuchanan, Jan 27 2009 Coin sorters would have a hard time with these.-- phundug, Jan 27 2009 //I just lost two Euros under the fridge//
Good; in this volatile market, it's nice to have some "cold cash".-- phundug, Jan 27 2009 Try the Aussie 50c coin, they never roll far.-- simonj, Jan 27 2009 //There's a couple of Brit coin with flat sides too... 20p and 50p, from memory?//Not since the twelve-sided three-penny bit, which probably went out of circulation before 1971.-- AbsintheWithoutLeave, Jan 28 2009 Parabolic and hyperbolic coins of infinite size?-- nineteenthly, Jan 28 2009 <fascinating and almost relevant fact> 50p and 20p have an odd number (7) of slightly curved sides so the 'diameter' is the same all the way around - I believe this is so the don't get stuck in coin sorters and coin operated machines </faarf>-- MadnessInMyMethod, Jan 28 2009 Gomboc shaped they will even show the same side every time!-- loonquawl, Jan 29 2009 I like paper money. Honestly I can't see why coin gets so much attention these days. *folds bills into approximation of gomboc*-- Spacecoyote, Jan 29 2009 I like paper money too... but in the UK the most useful of all notes, the single pound was removed from circulation and replaced with a hideous lump of a coin some years ago. In the Euro zone, there is a plethora of small coins which were obviously conceived by a total moron. I have given up trying to tell them apart and instead just offer handfulls of them to the cashiers and grin helplessly as they expertly pick through them. When these coins hit the ground, they seem to simply vanish..... could they not at least have small magnets embedded in them, if they won't make oval versions?-- xenzag, Jan 29 2009 Canadian and USA'ian 25c pieces have traditionally been the same diameter/width with the result that vending machines located near the border are always ripped off depending on which is worth more at any given time.-- FlyingToaster, Jan 29 2009 xenzag - I agree, I don't think it is possible to tell the coins apart. I guess that each country was sent off to design one coin, they all came up with the same design but went ahead and made them anyway.
FT - UK 10p pieces also fit neatly into many quarter machines, saving around 10c each.-- MadnessInMyMethod, Jan 30 2009 //After a few more years you'll get used to it// We've had them since 1983. Make that a few more decades!-- MadnessInMyMethod, Jan 30 2009 random, halfbakery