Poison Dart Trap (CR 1):
Perception DC: 20
Disable Device DC: 20
Effect: Atk +10 Ranged
Trigger: Touch Automatic Reset (CR +1)
Poison: Shadow Essence (CR +3)
A CR 5 trap that is +10 to hit, with a DC 17 Fort save or take 1 Str drain and a DC 17 Fort save every round for 6 rounds or take 1d2 Str damage for each failed save.
I would say it can put the hurt on a party of 4 level 5 characters. Send a minion in first? Trap resets behind it. Delay Poison? Doesn't cure the Str drain and uses up your casters highest level spell slots. Restoration? Not available yet.
Yeah its a low level example. I haven't gone into the trap section in depth yet and this is what I came up with on short notice. Higher levels, just mean more creative ways to add CR to the trap. At least from what I've gathered so far.
I personally like my rogue, she has been a great asset to the party. In our last encounter, her first attack was to crit with a shuriken. We use the crit hit deck and the result was "dazed for 1 round". I did a decent amount of damage to it and shut it down before its turn. The party was extremely grateful the lich couldn't cast for that round, as we proceeded to kill it before its next turn.