Is there a website or service that computes how much a megahash/s will earn you daily on average, taking into account the current difficulty?
If you know how to use R:
if not, amount of coins from a given rate of Mhps:
block value * 10^6 * hashrate (mhps) /(current difficulty*2^32)
In the case of 1 Mhps and 1 second (ie 1 Mhash), and current difficulty and block value:
52 * 10^6 * 1/(434882.7*2^32) = 2.676936e-08 coins.
This will of course change as difficulty and block value change, and keep in mind these are average expected values. Also there is a history of difficulty somewhere, but i can't find linky.
Hope this helps.