Someone already answered how far the light will go... across the room most likely if its a cheap one bought at a dollar store or radioshack., really depends on the exact output power, quality of optics, etc etc.
Now qume.. are you telling me you have never looked at those scanners at the supermarket?
A 5mw laser is dimmer than the sun in the sky, and the same logic applies: Don't stare into it... but personally, I'm not afraid to go outside on a sunny day for fear that I might get a bright flash from the sun.
cb19: some reds are better than others. A 5mw red's main use is to play with your cat.. and it will work well for that.