Two new Darkmoon Faire cards have cropped up in the latest Beta build, 8885.
[Darkmoon Card: Death]: Each time you deal damage, you have a chance to do an additional 787 to 913 Shadow damage to targets with less than 35% health.
I can see this coming in handy, especially since it works for casters, range and melee alike. There are many times when a group wipes because they couldn't get a boss down quite quickly enough, for example. It would also be useful for soloing, just to speed up the process and give a little boost.
[Darkmoon Card: Greatness]: Chance to increase your highest stat by 85 for 30 sec when dealing or taking damage in combat.
I especially like this one. It would work for anybody, and adds a bit of individuality I think. Granted, 85 isn't the highest bonus to a stat you can find on a trinket, but it has the potential to boost stats that existing trinkets don't.