You can mine Vanillacoin (blake-256)
the 6990 will do around 2.8GHASH.
Whoa! Pretty good.
So why is GPU mining all of a sudden profitable?
The last time my 6990 made this much was at like Jan 2014 mining Dogecoin.
No it is not profitable. Vanillacoin's algorithm isn't Blake-256 but WhirlpoolX. However, I have no idea of what would be your hashrate.
I was whirlpoolx, and it has shifted to blake256
But mining decred may be better....
GPU mining is profitable again, due to rise of BTC and huge rise of ethereum (which absorb most of amd hashrate power from GCN cards) I think : hashrate for other coins is lower due to the rush to eth mining, which leave space for small miners on others coins.