What tools do distributed programmers lack?

I have a dream to improve the world of distributed programming :)

In particular, I'm feeling a lack of necessary tools for debugging, monitoring, understanding and visualizing the behavior of distributed systems (heck, I had to write my own logger and visualizers to satisfy my requirements), and I'm writing a couple of such tools in my free time.

Community, what tools do you lack with this regard? Please describe one per answer, with a rough idea of what the tool would be supposed to do. Others can point out the existence of such tools, or someone might get inspired and write them.