In reply to Paulos:
I favour the DMM classic rope bag. I have tried many but this is certainly the best.
1. It's a backpack. The tarp and rope go inside and you can put a lot of other gear in there too. Two half ropes fit. A sport rack fits. So do guide books and shoes. Probably not all together but your partner's carrying a pack too, right?
2. You can deploy it as a bucket if you want to.
3. The tarp is entirely detachable so, if you're walking in with a real, bigger or better backpack, you can "borrow" the DMM tarp to wrap up your rope. This is surprisingly useful.
4. The tarp is HUGE and has four coloured attachment points.
5. The construction and colouring is top-notch.