Re: web site regulations
Are you talking about the images from Google itself, or images returned in an image search? If it's the latter, then you (strictly speaking) need to contact the copyright holder and request permission if it's not explicitly granted already.
That said, as said above if it's a not for profit site / personal site / site small enough that no-one will ever care, it's very unlikely anyone will make a fuss.
Save the whales, feed the hungry, free the mallocs.