Bike sculptures - ideas wanted

With the first stage of the Rás finishing in Portumna - where I work as a teacher (second level) I am currently undertaking a slightly mad project with one of my classes. We are aiming to line the route into the town with as many old bikes as we can get our hands on - each bike will be decorated by the pupils, working mainly at lunchtime and after school. I'm hoping it will do 2 things - raise awareness among our pupils and people of the area and also have a bit of fun with metal sculptures etc. So - I'm looking for ideas, at a very basic level we will simply spray the bikes but I would like to do something more adventurous with some of them. Maybe you have seen some projects like this abroad or online - or have some ideas yourself and would be happy to pass them on. I will post pics of our results over the weekend.