The problem with our postcard and key ring idea is that they were ideas that didn't fit in with the whole spare time issue. The brief asks for you to promote last minute as a a site where you can book more good stuff in your spare time. So now we know that we need to find out when people are most susceptible to the offers and promotions. Capturing these spontaneous moments are key to a successful project.
We have another idea that pretty much meets the requirements and will update when it has progressed.
I have more pressing issues at hand.