Has there been any mumblings about Ninja tricks that follow the alchemist line of improving poisons or poison use? That's a pretty Assassin-esque and ninja-type move, but right now the Alchemist is the ultimate poison guru.
It's sort of a let down...
Well you can always ask your DM to let you take the Poisoner Archtype for Ninja, maybe trade it with no trace, which is like trapsense.