I'm on the search for some sort of rain protection that I can throw on without taking off my pack. I'm picturing either a poncho that covers both me and my pack, or a rain coat with a split back to wrap around the backpack suspension. Does anyone make anything like that?

If you haven't seen it yet, you might want to consider The Packa as a great alternative. I have one in silnylon and one in eVent and love it. It has huge pit zips to give you as much ventilation as possible and you can put it on your pack in "pack cover" mode and quickly don the jacket part while hiking if you need it.

Like any pack cover, it works best if you use a hydration bladder and tube...It can be a little challenging to get a water bottle out of the side pocket while wearing it.

great product. dual use. super light.

http://zpacks.com/accessories/groundsheet_poncho.shtml