I like brainwallets, because eventually some idiots will use a stupidly simple key.

Coder create a script that grinds names and english words together + 0-9 then inserts keys into a bitcoind worker instance to be validated. You have another script to automatically empty the wallet to your cold storage addy / torwallet periodically.
Depending on the amount of idiots (lots) and bitcoin uptake it can be more profitable than mining.

I figure the same will be eventually true for privkey, but current efforts have yielded nothing.

I personally have not done this but I see a lot of people gearing up for it if brainwallets keep gaining popularity.