Ok, so I know this is a bedroom but it's a great use of space for a small room. I particularly like the use of the dead space behind the ladder for shelving. It could also be a cool idea for a kids play room.
DIY Storage Bed Frame - best use of space of your room. If you have basic power tools (circular saw, drill machinery, electrical screwdriver) and know the basic woodworking skills, you could get the job done by yourself in just a weekend.
built in beds make this room more of a hang out with a couch as the main space and not the bed. This would be a great space in a basement area, providing extra sleeping room when family comes to visit or for sleepovers.
DIY twin bed with storage - interesting idea to make shelves or cubbies instead of drawers like a captain's bed - easier! On a Queen or King bed, would be a big gap in the middle, though - (HIDDEN STORAGE)