We have a fish tank that we want to get rid of.  We got it at a yard sale a few years ago but never set it up, so I'm not sure if the seals are still good or would need fixing.  Regardless, it could also be used for a terrarium or to house small reptiles.  It's 30" across, 19" tall, and 12.5" deep.  We also have a hood and a light (I'm not sure if that works either, though).