Ethereum

http://www.mycryptobuddy.com/EthereumMiningCalculator

https://etherscan.io/chart/difficulty

http://wccftech.com/ethereum-mining-gpu-performance-roundup/

https://www.cryptocompare.com/mining/sapphire/radeon-r9-295x2-ethereum-mining/

https://www.cryptocompare.com/mining/bitmain/antminer-l3plus/ bitmain sells litecoin asic miners

https://www.nicehash.com/?p=calc

https://www.reddit.com/r/EtherMining/comments/3goigz/anyone_interested_in_a_mining_guide_for_arch_linux/