The Deutsch paper I quoted before was where I first heard of the Bekenstein Bound which Eric Hughes mentioned. According to Deutsch:
"If the theory of the thermodynamics of black holes is trustworthy, no system enclosed by a surface with an appropriately defined area A can have more than a finite number
N(A) = exp(A c^3 / 4 hbar G)
of distinguishable accessible states (hbar is the Planck reduced constant, G is the gravitational constant, and c is the speed of light.)"
The reference he gives is:
Bekenstein, J.D. 1981 Phys Rev D v23, p287
For those with calculators, c is approximately 3.00*10^10 cm/s, G is 6.67*10^-8 cm^3/g s^2, and hbar is 1.05*10^-27 g cm^2/s. N comes out to be pretty darn big by our standards!
Hal
The problem I see with this is that there is no connection between a black holes mass and surface area (it doesn't have one). In reference to the 'A' in the above, is it the event horizon? A funny thing about black holes is that as the mass increases the event horizon gets larger not smaller (ie gravitational contraction).