Well, since this is an open invitational, I'll bring up my biggest pet peeve. It's a little embarassing, as apparently it doesn't bother anyone else...

The light system.

Yes, I know the earth is round. Yes, I remember reading something where it was mentioned that Poser doesn't have any limits as far as depth and width of scene. But frankly, I don't see too many renders where someone is trying to render something so vast that it shows the curvature of the planet. I must be missing them.

Why the devil can't the light system be based on a flat xyz coordinate system?

Okay, it's out. My secret pet peeve that demonstrates my total inadequacy with lighting.

kalonart.com