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."