Its not a case but more of a process, I've been reading about this and was wondering if anyone has tried it? Its not cheap but some of the pricier smartphones it could be worth it if it works and no case to mess with. The company is called liquipel.
http://www.liquipel.com/ currently I use a Casio G'zone which I feel confident is plenty water resistant but keep considering a smartphone and was thus looking for a way to protect it if I did make the switch.
Darren