Businesses telling consumers when peak periods are (a free* idea)
Everyone hates queueing, whether it is in a line at a bank, or waiting on the phone. A simple piece of transparency from businesses could reduce queueing and increase efficiency (and therefore profitability!)
All we need is for a business to post on their door / email their customers, a simple graph showing relative peak periods. They don't have to give actual figures. As long as the consumer can see when it is busiest and when it is quietest, they can make an informed decision as to when they visit/phone.
A widget shop gets most of their customers between 9.30am and 10.30am. But customers mistakenly think that the busiest time is between 12 and 1pm, their lunch break. So many customers do their widget shopping during their morning break to miss the much worse queues at lunchtime. With a graph on the widget shop door, they'd see that the the shop is almost empty between 2pm and 3pm, and some will choose to visit then. This will balance the load and make everybody happier.