What about offering support for SHA-3 coins that are currently GPU only with no ASIC support yet. MaxCoin would be an obvious example. There's a cudaminer version with SHA-3 / Keccak support. It flies on a decent GPU rig.
I think most, if all of the GPUs in GM's farms are all AMD GPUs, so not sure if it would be as profitable or not, although Nvidia 750Ti's are pretty cheap and might be an option to set up rigs with those specifically to mine X13 and Keccak algos as they are pretty energy and heat efficient and give out better hashrates than the AMD cards, that are also double the price.