Looks like only AMHash, Bit-x and KNC Cloud are the only legitimate bitcoin cloud mining services left in the game and KNC Cloud are more of a hosted mining service with a 6 month contract. So, basically just AMHash and Bit-x.
By far BIT-X.com has a larger market for GHS trading (there is much less of a bid/ask gap).
There are no contracts so you could mine for a day or a year then resell your GHS!