Accessory structures for connection to straps of user-wearable accessories include a module, a first strap engagement structure disposed on a first side of the module, and a second strap engagement structure disposed on a second side of the module. The module may comprise at least one of an integral accessory device and an attachment feature configured for attachment to a separate accessory device. The strap engagement structures are configured for connection to straps of a user-wearable accessory. User-wearable accessory systems include such an accessory structure and a user-wearable accessory to which the accessory structure may be connected. Methods include the formation of such an accessory structure. Additional methods include the connection of such an accessory structure to a user-wearable accessory.