Dendrobium teretifolium (the "bridal veil" or "pencil" orchid) The individual flowers aren't pendant, but the whole plant is - and is capable of blooming a couple of times a year, a big specimen can be in bloom all summer. Also Epidendrum parkinsonianum - again, it is the whole plant that is pendant. A specimen-sized plant in bloom is spectacular, and even in when not in bloom, quite attractive.