I took this idea from a bunch of ideas I found on the forums. I was inspired by everyone!
It would be cool to have a pet like a carrier pigeon that could deliver items. The pet aspect might be that we have to take care of them to level them up. Then, when they level up, they can learn new skills. The mailman aspect would be to have the pet's skills deal with delivering items. For example, a pet with "Delivery IV" might be able to deliver a package in 10 minutes, as opposed to a pet with "Delivery II" which would take 20 minutes.
I'll update this post as you guys give more ideas!