Sure, it may not be the most secure place to stash your valuables, but you can't argue with the coolness factor of building your very own sliding picture secret panel. Instructables reader robdavinci put together this clever project for Instructables' secret compartment contest.
The door is driven by a continuous rotation servo motor with a pulley system. As is, it uses a simple switch to activate the panel. As its creator notes, the project could also serve as a great base for adding more sophisticated controls such as motion sensors or wireless remotes.
Hit up the post at Instructables for the step-by-step instructions.
Sliding door secret compartment [Instructables]