New here. 
I'm mining with cgminer (altcoins) on linux and am seeing a lot of variability in price between different coins to mine.  One day LTC are worth the most to mine, one day, LTC, and the next, MNC.  I would pay for a program that finds out the most profitable coin to mine (that's the easy part as there are multiple sites telling you that all ready) and instructing cgminer to mine the most profitable coins. 
Only problem is that C# is windows, isn't it.  If you could do that for windows, though, I might be able to get my rig running that.  And I'm damn sure that lots of people would want your product.