To start off on a relatively low note, Yerba Mate. Usually used as a tea from the leaves of the Mate tree (Yerba actually references the leaves), it is also used as a supplement for cognition and energy.
When looking at Yerba Mate, its healthy and nice yet not interesting. Compounds in Yerba Mate are also found in green tea (mostly the green tea catechins) and coffee (ferulic acid, chlorogenic acid, caffeine, etc.). Yerba Mate is like half-way between coffee and tea, in regards to health and stimulation.
Its connection with cancer of the esophageous, also present, is mostly due to the heat it is drunk causing thermal damage and possibly contaminants.
Speaking of ferulic acid, binding two of them together yeilds curcuminoids; curcumin is merely these two molecules connected by a carbon, as denoted by curcumin's true name of diferuloylmethane (di- as in two, feruloyl denotes the ferulic acid groups, and a methane bridge between the two).
Curcumin is quite the little panacea. Seems to have beneficial effects in most disease states and potent anti-cancer effects. It is it's own class of polyphenolic, distinct from the bioflavonoids like quercetin or the anthocyanins like cyanidin; thus it has some unique effects that these two classes do not have.
The only cautionary advice I give in looking at the curcumin page is to look at the models used in research. Curcumin may be a panacea in diseased states, but surprisingly little research is done in already healthy people. The cancer effects (chemoprotective) seem to extend to healthy persons as well, but effects on lipid and carbohydrate metabolism may be dependent on disease states.
Finally, Cissus Quadrangularis has finally been added after quite a bit of pressuring. It seems to be used a lot by fighters (MMA, from what I hear) as a 'joint-healthy supplement', and the preliminary evidence seems to agree with this. Most interestingly, it seems to be able to increase bone regrowth rates; increasing recovery from fractures as well as exerting a bone sparing effect in osteoporosis. A herb with preliminary studies on it, but looking very interesting for joint and bone health.
Both Cissus and Curcumin both seem to have phytoestrogenic properties, but at does above what is normally recommended to supplement; just so you know.