Another handy thing you can do with Power Auras is monitor weapon enhancements like poisons.
It's fairly straightforward.
Set your "Activation by" to "Weapon Enchant". Leave stacks at ">=0".
For your mainhand, set it to "main/poison" (and "off/poison" for your offhand) - it will monitor if you have poisons on that weapon, regardless of type. You can specify poison type if you want to - perhaps for battlegrounds/pvp, you want to remember to use crippling/numbing poison instead or something (you can also make a separate aura to remind you in battlegrounds if you so desire). I selected "Invert" - this means it will only show when I don't have poisons on my weapon.
You may have noticed I've also circled something at the bottom of the image - this allows you to make your PA notification spec specific (more on this later, as I don't have dual spec on my rogue, but I do use this feature on my priest).
Note: If you select "Use own texture", you will have to apply poisons to your weapons, unequip and then re-equip them before the textures will show up. The texture will be that of the weapon, in the case of a weapon enchant, just like the way it displays as a buff icon. (I originally wrote this several months ago and I'm not sure it's still an issue with the current version.)
Version:4.4; anim1:2; icon:INV_Sword_43; buffname:main/poison; begin:3; x:-66; bufftype:5; owntex:true; PowerType:0; combat:false; size:0.26; y:190; inverse:true; anim2:2; finish:4
Version:4.4; anim1:2; icon:INV_Sword_36; buffname:off/poison; begin:3; x:74; bufftype:5; owntex:true; PowerType:0; combat:false; size:0.25; y:190; inverse:true; anim2:2; finish:4