I have been working on this one for a while for my own needs, but managed to turn it into usable package for low-poly modelling.
LowPoly Factory is a procedural content generator specialized in lowpoly landscapes. The idea is to easily generate the scene and then tweak parameters/materials and do manual work to make end result original. Each object is unique, but still based on parameters you specify. There is an option to bake materials to vertex colors, which makes it easy to import models to your 3D game engine of choice.
Come on, you just clicked the first link to shoot it down:D I switched the links for convenience - the tree generator is free, it is also the single most interesting part of this add-on. It does pines, oaks and palms. Hope you get to try it since it looks like you were interested.
Thanks to all who have downloaded it, also to 5 people who got the complete pack.