Dwarven Forge is a manufacturer of fully hand-painted, and ready to use out of the box, miniature terrain in 25 mm scale designed for use by miniature and roleplaying gamers. The main Master Maze range is for Fantasy gamers, and they also produce a small sci-fi line.
They have also in the past made prepainted resin 25mm miniatures and d20 fantasy adventure modules.
From Dwarven Forge's website:
"Dwarven Forge was founded 10 years ago by artist Stefan Pokorny, a medieval fantasy devotee -- and an avid Dungeons and Dragons enthusiast. As a classically trained, professional painter and sculptor, Stefan decided to create "real" dungeon terrain that would equal his incredible 25mm tall hero figures. After many months of painstaking design, sculpting and painting, he introduced the world's finest pre-painted miniature terrain in 1996."