Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
SpeedTree - SpeedTree is a powerful toolkit used to create 3D vegetation for video games, films, and animations.
JPEGView - JPEGView is a small and fast viewer/editor for JPEG, BMP, PNG, GIF and TIFF images.
Tree Studio - Easy 2D Tree Creation
ACDSee - ACDSee is an image viewer that uses very little system resources, and it has a small, sleek size that won't take up much space on your system.
The Grove 3D - Model or grow adaptive 3D Tree models for use in CG renderings.