I’m not sure if you’ll like the idea, but here in the forum, one of the best ways to grow your Bitcoin is by lending to trusted users.

You might want to check out the Lending Board..

As far as I know, there’s only one major active lender here, so this could be a good opportunity for you. Although, it’s considered high risk since most loans are unsecured, but that lender has been doing it for a while, so it seems to be profitable I guess.