[research] middleware

I’m curious on what middleware is out there for game development. I know of the bigger stuff like Havok, SpeedTree, Nivida GameWorks and AutoDesk products, just to name a few, but what else is out there?

Is there perhaps middleware for weather and clouds? City building? Doesn’t matter, I’m just curious what else is on the market that doesn’t have a big marketing name to it.

Also, what middleware is included with Unreal (products built into the engine) and what is integrated (products you have to buy and license, but ready to use with the engine)?