Poison ivy berries are eaten by songbirds in the winter. To me, that's enough to justify its existence and actually make me like the plant.
I have this vision of one day protecting my yard by shrubs and cedar trees inundated with poison ivy. I always figured I'd be able to point out the criminal who broke into my house and stole my lousy stereo system in the line-up.
"Yes, officer, he's the second one there. The one covered in red bumps that is itching really badly."
If that doesn't convince you to keep it around... my cousin says: To kill poison ivy you can use straight white vinegar (it will pretty much kill any plant), only humans are allergic to it and goats love to eat it.
Back to the Poison Ivy Tutorial.