In the comments for my last battle report, Ghengis Vaughn said...
According to Wikipedia, it's a Belostomatidae, or "Giant Water Bug". It lives in North America, South America, and East Asia. Those "vessels" on it's back are eggs, which the male carries around after the female lays them there. It's also known as the "Toe Biter" bug. Depending on the sub-species it can be anywhere from 2 - 12 cm long.
Here's the full article: http://en.wikipedia.org/wiki/Belostomatidae
"They often lie motionless at the bottom of a body of water, attached to various objects, where they wait for prey to come near. They then strike, injecting a powerful digestive saliva with their mandible, and sucking out the liquefied remains. Their bite is considered one of the most painful that can be inflicted by any insect; the longer the bug is allowed to inject its saliva, the worse the resulting bite, and as the saliva liquefies muscle tissue, it can in rare instances do permanent damage."Sounds like a proto-Tyrannid to me. :)
I've never seen one in person, but I haven't been looking (or wading barefoot through creeks) either. :)