I really hate the smell of spraypaint, it can even give you deadly dideases such as cancer or severe lung problems. H2O was created to solve this problem. It is a water based spray paint, so you don't get the odor that comes with oil based spraypaint. It also means that it can be used on a larger range of materials such as foam board, because your average can would just dissolve it. It even washes out easily with soap.
Krylon make H2O paints in a nice range of simple colors so you can paint the rainbow! They also provide a very clear color without having to use too much paint, it's always a nice smooth paint. There is however one thing about H2O that annoys me, as an artist I use spraypaint for stencils and such like. The problem with H2O is that you can't layer different colors it very easily, the paint just doesn't soak in. Despite being such a great spray paint, H2O just doesn't work for my purposes. I now realize that it's intended for more simple jobs such as painting a wall. At 5 bucks a can it's not exaclty cheap either but if your looking for a nice finish paint for a room or something, H2O is the way to go.