Just a question that can apply equally to bikes,cars, trucks and even travellers by foot. What is the most useless piece of equpment or tool that you have bought or attained and the flip side of that is what is the most useful? Lonely Planet Guide For me the Lonely Planet Guide for Australia slotted perfectly into both categories.The bastard thing is about the size of a Bible bodge taped to a Koran and weighs the same as a house brick. Useless Even though I carried the bloody thing for over six months, I never needed to open and peruse its knowledge for anything. Essential To remove my bikes rear wheel to repair a chain or puncture, required me to detach a pannier and place it under the bikes bashplate, then lift the bike up onto the pannier to clear the ground ....all it needed was a spacer about the size of a bible and Koran bodge taped together. Yep The lonely planet guide fitted perfect.