Online cabling supplier Electronics and Cables offers Category 5e and Category 6, shielded and unshielded, twisted-pair copper patch cords with 90-degree-angle connectors.
The company characterizes the cords as "a good way to save space behind and between components. Each patch cable is terminated with a high-quality, molded 90-degree RJ45 [8P8C] plug."
It further says the patch cords are "a good solution for taming cable runs within networking racks or cabinets," as well as being "popular among factory-automation systems." They are wired according to the T568B termination scheme.
The cords are available in three different termination configurations: right-angle up-to-down, right-angle down-to-straight, and 90-degree down-to-down. The full product offering can be viewed here.