If I were to write a novel
How much time gets spent staring in a placidly bovine fashion at a concrete wall while waiting for subway trains every day? If we consider London, there are roughly a million people travelling a day, each waiting for maybe five minutes - that's 100,000 man hours a day. While chewing the cud in this manner, one finds oneself wearily reading and re-reading the same inane advertising drivel.
If I were to write a novel, I would spend all my meagre advertising budget on renting out all the billboards for a single platform for a day. I would display the first chapter of my book piecewise, starting at one end of the platform, so that people could begin reading, progressing crabwise in lockstep from billboard to billboard, hungrily seeking the next installment. At the very end of the platform, I'd hand out free copies of my book.