As I mentioned on here I recently went on an almost 2 week trip to Argentina & Uruguay. Great trip overall!
And I can honestly say that the REI Stuff Travel Day Pack made the trip noticeably better.
Here is why:
I actually put this little pack in my big pack. My big pack had all my stuff (clothes, bathroom items, wires, cords, etc.).
The little pack collapses into itself and is about the size if a man's tennis show! But when you expand it the pack is a medium size backpack.
I used the day pack to go on excursions -- a day trip into Tigre on the river delta, a half day tour around Buenos Aires, a looooong day of hiking through Iguazu National Park, and so on. I'd throw in some extra TP, my rain coat, some immodium, a bottle of water, some peanuts, a banana, etc. If I needed something to stay dry I put it in a ziplock inside the pack. If I needed the whole pack to stay dry I could take out the raincoat and put it on over the whole thing (me and the daypack).
Great system!
Anyway, this daypack set me back only $30 and has quickly become a prized possession (which says a lot because, as you know, I am minimalist!).
Here is a pic: (left is collapsed; right is fully open)