I was pretty sure Walt was going to hold the "ride along" over Hank's head - and that was a big reason why Hank didn't want to tell the rest of the DEA - but I totally forgot about the medical bills! That "confession" was incredible. I guess that pretty much puts the kibosh on any possible reconciliation between Skyler and Marie.
The waiter at the restaurant!

My only complaint about this episode, and it's a big one, is that the whole ricin revelation was way too much of a stretch. No way Jesse just figures all that out.