Certainly, the late great Dr. Ian Stevenson and those great academics who follow him have documented the phenomenon of children, who are similar in many ways to the persons whose lives they remember. The similarity seems to reside mostly in their eyes as many have mentioned in this thread. Some cases have also documented certain birthmarks and birth defects as being very similar to the person whose lives they seem to have shared. See the following link:
http://books.google.com/books?hl=en&lr=&id=JoFUIvIxPEwC&oi=fnd&pg=PR11&dq=related:hUArs0SwHvAJ:scholar.google.com/&ots=Ki21ZzATTB&sig=NWQqiGqBy-UpuvuORoug_2byzxg#v=onepage&q=&f=false
If I knew how, I would be able to shorten this and other links.
There have also been documented cases where adults have discovered uncanny similarities between themselves and their past-life counterparts. Anyone interested in this aspect of reincarnation can find numerous videos at
http://www.youtube.com/pastlifeforum
Also, one can find links to books and PDF documents in this site by jumping over to BOOKS and LINKS about reincarnation.
Aside from the above homework assignments,

I have to personally admit that I'm beginning to believe that there is something of this phenomenon that seems undeniable. And, I've discovered that even some identical twins, who share the same genes are often different enough to indicate that there is something else going on besides DNA.
As Ailish mentioned earlier in this thread, it can be said that appearance may also be totally different, but the vibrations are the same. [Forgive me, if I didn't paraphrase your words exactly.] You may have heard the phrase, "Abuse it -- you loose it.". Perhaps, when someone abuses their appearance in a previous life, they may end up looking entirely different for the sake of a lesson that needs to be experienced and sorted out. Or, they may have something to teach us.
Another theory suggests that people come into this world when the physical characteristics acquired through DNA happen to match the particular soul of the reincarnated subject. Such might be evident in deceased relatives, who are reborn into the same family. Perhaps, DNA is a function that works with reincarnation. This may all be conjecture, but it presents some interesting theories which warrant deeper inspection.
As for my personal experience, I'm very hesitant to present myself as being reincarnated. However, some time ago, my grown sons found photographs of a minister/reformer, who made public the corruption of a political machine in New York City called Tammany Hall, which happened 100 years ago to the day of this discovery. The similarity appeared not only in facial features, build and demeanor, but also in behavior and a troublesome affinity for challenging certain powerful elements.
When it comes to vivid, recurring dreams, I seem drawn to the 5th Connecticut Continental Line troops during the American War for Independence, where the same crusading behavior is evident. Of course, this may be simply because in 1978 I uprooted my family from the midwestern U.S. to an area steeped in history -- except for the fact that I knew about a minor skirmish that happened in a small coastal town called Cos Cob before someone found an obscure book, which detailed exactly the same fight in exactly the same place. In this case it is nearly impossible to determine who the rebellious soldier was, or what he looked like, but the dreams indicate a person of the same build and face, but without the beard that time. One might say that the crusading behavior is still evident.
There is also a theory that a person might be injured in exactly the same way as their former self. I can only bear this out from my own experience, when I was 14 looking in a bathroom mirror once. I somehow imagined how I would look later in life, after certain injuries which left severe scars on my face. Coincidence? Serendipity? Synchronicity? How can we really determine what it is, but that we know it happened?