NAF Oestress works on the grumpy mare I ride, she used to be on it all the time and was much better (we once ran out when she came into season, she was a nightmare!). She's not only on it when she's in season and it still works!
I was recommended Hormonise by some HHO peeps and I have been really pleased with the effect.
I don't think they're miracle cures BUT it's definately taken the edge off