Even when I was at college me and my lovely house mate George had a colouring book and used to get through the odd hangover by colouring. Its a really relaxing thing to do.
Its a bit of a long story that I won't go into, but my friend at work brought me a colouring book this week. Its the most fantastic colouring book at have ever seen. It not only encourages you to colour, it also had plenty of free-style doodling moments.