I am starting this thread so that it pops up when someone does a search.

It will rain at some point while you are traveling. Some people prefer a big poncho so they can just throw it over their backpack too. Others prefer umbrellas – to each his own. I have done both, but I now believe that both are pretty much a waste of space and weight. My reason? My personal preference is to bring a windbreaker (which I have previously sprayed to make it water repellant) and I just spray water repellant on both my big backpack as well as my daypack. (I just use my hood on my jacket (or a baseball cap – which is something that you will rarely see worn in Europe) to cover my head). This way you can use the jacket when it rains, and it is not extra weight – since you will have brought it anyway. The only way that this saves space is if the jacket is waterproof – so make sure to buy one that is waterproof or to spray your windbreaker down before leaving home. I also like to bring a waterproof clear plastic zip-lock type bag that is specifically made to hold a normal sheet of typing paper. That way, you can just rip out the part of the Guidebook that has the map of the town that you are visiting and carry around the map (in the plastic) so it doesn’t get wet when it is raining. This is also what I do if I arrive in a town and I get a hostel lined up and I am making my way to the hostel and it is raining (this way, your directions don’t get smeared).