i was in my hobby shop and they have some 'sticky paper thing' i dont know what it is called but one one side its a non-stick surface. you actually put this thing in your printer, print your decal on, cut out decal and peel of non stick side and stick decal on your model, pretty cool

Yeah, sounds like an interesting idea, but those "sticker-type" decals could be overly thick, or so I remember when I was little noseminer and my friend had a couple of models with sticker markings and those buggers were thick!
One problem I can think of is the adhesive in them being too tacky, and you can't correct a decals position if it gets to a wrong spot.

that is a good point you have about them being to thick, i dont remember the material you put in the printer being thick, but i only took a quick glance at it, what i do is print something out then transfer it onto a note card and use it as a stencil then paint on the decal, more authentic..

I agree to Emeritus, on top of that you have to check, on top of thickness, how this "stickers cope with weathering...
Ciao