I would like to suggest that instead of the number of BitCoins generated per block being halved every 4 years, thus being 50*2^-(n/4) it will be 50/(n/4).
  This will have no effect on the first two periods (first 8 years) but will from then on generate more coins, but at an ever slowing rate.
  This may solve several problems, it will keep miners motivated, it will generate some rate of inflation which will deter hoarders which destabilize the value of the BitCoin.
  While in theory this leads to infinite growth of BitCoin supply, which will eventually overflow 63 bits, it's logarithmic growth, so 63 bits will not overflow the the lifetime of the sun. IEEE double precision will be able to represent the total number of Satoshi for another 10000 years. (Does anyone use doubles for exact BitCoin count?)