Of course, every culture that has adopted Christianity has put their own spin on what Jesus looks like. For example, in European artwork, Jesus is depicted as being white. In African art depicting Christ, he is sometimes portrayed as black (incidentally, this is probably correct. Being of Middle Eastern descent, Jesus was a black man.) For every culture that has adopted christianity (or had Christianity forced on them), there is a different way of depicting Jesus.
Of course, as people, we have the tendancy to see faces everywhere, even in random images. It's hardwired into our brains, and it's part of the reason we are able to recognize different people. It's not a new development, either, but it's been that way for quite a while (we've known about the man in the moon for millenia). So, it's not surprising that we see Jesus's face in many places -- as humans, we see faces everywhere, and Jesus has a distinctive and well-known face (at least, the European version does; I assume the other types have equally distinctive and well-known faces).
Of course, this w/u is following in morgandorf's footsteps, in that it doesn't answer the fundamental question. Either (a) people who have constantly been exposed to images (of what some artist thinks Jesus looked like) naturally begin seeing that image everywhere, or (b) God knew that this is how we would depict Jesus, and thus naturally made things that looked like what our depiction of Jesus would look like, 2000 years in the future.
Out of curiousity, do Buddhist people see the face of Buddha in random objects? Do Jews see Yahweh (or an artists rendition of him) in their potato chips? Do Discordians see images of Eris right before they partake of their hot dogs? Inquiring minds want to know!