Seems to me that all those services sell miningpower for more than the bitcoins it will generate is worth. That means you don't even need the mining rig. You can just sell the "hashing power", use a share of the money for the sale to buy enough BTC on mtgox, and feed those BTC back to the customers at a rate that corresponds with the hashing rate they were promised.
**** a week for dual core processing is way below the actual BTC net income, I would be "losing" in a way, but I want to test how accepted is this kind of market.. And if it works out, I would rather have the money on my PP account without going through fees/convertions to get the extra hardware from a reliable source..
My 6870 does 280 MH/s - a dual setup should be able to do 500MH/s at least!
I would be interested, just as a short question: Who pays paypal fees and do you accept weekly payments too?
Edit:
Would you agree to a system similar to vladimir's? You say, you mine at xxxMHashes/s for a period of time and just pay daily (or even weekly) what these MHashes/s would generate in BTC. This means you can rent for example 400MH/s but still have 100MH/s for yourself/variance and on the other hand customers don't have to hope that you have a "good day" or "luck streak".
Are you sure about this..? I cant get the miner to report over 220 MH/s, these are NOT black editions, neither they are overclocked.. Deepbit reports from 190 to 360 for some reason I still dont understand..