Resource Furniture has lots of space-saving furniture including the Passo ("Transforming coffee table with glass or wood top and metal frame. Adjustable to various heights, including dining, with two self-storing leaves.
Love this idea! Take two IKEA Expedit bookcases, frame in MDF, paint, attach casters, and bolt some stained to the top. Designed by the amazing Justine Taylor. This would be good in craft room or an office and maybe a kitchen island.