The Federal Austrian Railways (OBB) offers locomotive branding for companies and organisations. A fun example is this loco branded with the colours of the Austrian police (Polizei).
I took this photo in 2011 while waiting for a connection train in Graz. I came across an even more intriguing idea several years earlier. In celebration of the 2008 UEFA European Football Championship, 16 locomotives were branded in the colours of the participating nations. A heaven for train spotters who love to take photos.