Books. No books! Paper is extremely heavy with respect to its usefulness. Read your tourist guide before the trip and leave it at home. The only thing that I need from a guidebook on the trip are maps of towns. I photocopy these or tear them off the guide – there is no place for sentimentality here. On a long trip it is sometimes nice to have something to read. When this mood hits me, I stay a day or two in some hostel where they have books to lend.