I ran across a mention of the Passport and Reality gallery, which shows people's photos from their valid passports side-by-side with what they look like now.
I have a particularly unrepresentative passport photo from 2001 (my passport expires this summer), so I knew I had to do my own comparison.
As with most of the photos in the gallery, it doesn't even look like the same person. Of course, no one looks good with Serious Face.
Funny thing is I've already changed my hair since the "recent" photo shown above. Now my hair is medium brown with chunky blonde highlights and I've been wearing it curly. So I guess you you don't need ten years to change your look; you can do it pretty thoroughly in less than a year.
Sadly, there's only one pair of stamps in my passport, from a trip to Jamaica in 2006. When I renew it, I'm going to promise myself that I'll do more international travel in the following ten years. There are lots of places I want to go!