I came across my simple mini key generator tonight, and I'm having another play with it.
The naive version uses random() and outputs about 8000 valid keys per second on a single core of an i7-3960X.
I've been doing that for a while (with a python generator), trying to create vanity addresses with mini private key, but I had to search through large output files and the output was far too slow to find anything meaningful.
One thing is sure in my opinion - brain wallets belongs to past.
I'm pretty sure people still use them. Even better if they use something they use much heavier encryption (such as WarpWallet).
The idea of simply remembering your money is appealing to me (but I don't dare risk it for a large amount).