Accessory holders useful for facilitating the support and positional adjustment of secured accessories. More particularly, a positionally adjustable accessory holder for use with one or more accessories, preferably input or output devices, such as video displays, monitors, keyboards, keypads, laptops and the like. The accessory holder further allows for easy three-dimensional adjustment of two such devices to place the devices in relative positions more ergonomically desirable for a variety of users and workspaces, and features a counter-balance mechanism for balancing the weight of the secured accessories.