Yes, the site is called images.google.com. Go there, type in the name of the celeb/sports figure/famous person whose autograph you are interested in, followed by "autograph" or "signature". You should get numerous images of the person in question's autograph, often on pictures/headshots etc., that you should be able to print out on photo quality/glossy paper (or attempt to forge the sig to the object of your choice if you are a particularly shady character, and no I'm not advocating that).
In any case, few if any of the "signed" photos/headshots that are sent out, usually from the person's publicist, are actually signed by the person in question. They use an autopen at best, or have someone sign (forge) on the behalf of the person (usually some lowly assistant or some intern at the celeb's agent/publicist company), or merely mass produce the headshots/pics with the sig already printed on.