Taijiquan (太極拳) is the most popular Chinese martial art today, but very few practitioners of this elegant style have any of the legendary skills often attributed to old time masters like Yang Luchan (楊露禪) and others - once upon a time, taijiquan was known for its combat effectiveness, after all. Although reasons for this change no doubt include changes in society (laziness, lack of interest, mixing of styles, etc.), it is also likely that much important material has been kept "in the family" and not passed down to most practitioners - most glaring is the fact that Yang Luchan was famous for his spear prowess, but taiji spear is very rarely taught (or seen), if ever.
Ma Yueliang (馬岳樑), son-in-law of Wu Jianquan (吳鑒泉) and perhaps the most famous martial artist in Shanghai of his time, for various reasons revealed many sets and methods that are not well-known in other branches; notable are the original "fast form" (快拳) that he said he also saw the Yang family practice, a free-sparring method using a "S" moving pattern known as lancaihua (爛采花), and several spear routines (24 spear (二十四槍), 13 long spear (十三大槍), life-saving 3 spears (救命三槍)).
There also appears to be a cannon fist (十三炮捶) routine, several qigong methods (5 phases neigong (五行内功), 8 methods neigong (八式内功)), several sword routines (heaven and earth sword (乾坤劍), 7 star sword (七星劍), linking sword (連環劍), double swords (雙劍), partner sword (對劍)), as well as routines/methods similar to those in other styles of taijiquan (saber, sticky staff, various push hands methods, etc.).
As Wu style is an offshoot of Yang style, one would normally expect most material in the Wu style to have a similar counterpart in the Yang style (its direct parent style); today, perhaps someone does still retain such material, or else it may have been lost already.
Some Yang style lineages today do contain interesting, rarer material, such as the long form (太極長拳), which is performed faster than the slow form, as well as rare weapons, such as the halberd (戟). The various lineages, however, seem to have different rare material, making it difficult to discern the validity of each, which is often an underlying problem. Ma Yueliang himself noted that when he was young, he saw Yang Chengfu (楊澄甫) practice Yang style's fast form with his own eyes.