I have some AuroraCoins (AUR), minin' them on ghash.io. I want to turn them into BTC and then use BTC (no USD!).
Some exchanging site?
Trust me, I've been Googling, Binging, DuckDuckGoing and others and found nothing.
Create an account on Mintpal, they have a direct trading market: AUR/BTC. From Mintpal you can withdraw it to your own wallet or where ever you want to have it.
https://coinmarketcap.com/ is a good site to show the trading pairs of various cryptocurrencies on different exchanges.
Find an exchange that has the trading pair you are after.
Do some research into the history of the exchange, any SCAM alerts, previous users experience, check on https://bitcointalk.org/index.php to see what other users say about the exchange. Have a look at the support ticket response time.
Once you are happy you have found a suitable and reliable exchange, transfer in your altcoin, trade and transfer out your desired currency.