How to create Ethereum brain address?
Don't use a sha512 brainwallet generator like bitaddress.org to generate your brainwallet. Many people have lost their money by doing so.

Instead use a more secure salted scrypt like warpwallet.

For Ethereum, I made a warpwallet implementation here, that is available as a web version and as a go executable. For extra security you should generate the addresses offline.