Here is what they should look like (or something similar), in terms of length:
I have to admit to not having read all of the info on all of these sites - there is just so much out there! Now, just to find the time to delve into it all ;) However I felt some of these sites could be helpful, hence their inclusion in this post. Hopefully they can provide others a foundation from which to bounce off of. Just for the heck of it, also check out the history of shoeing horses - it could add insight into barefootdness as well; I definitely found it interesting.
On a personal level, we have kept all of our own current three horses barefoot as long as we have had them (1, 9, and 14 years), save for the odd temporary shod episode under very particular, special, and elite circumstances. We have never had a soundness issue with any of our horses (save for the odd time a farrier trimmed too short or a rare rock bruising). Ever. Despite their various activities. Coincidence? I think not. My personal belief is that nature probably does a pretty good job of providing our horses with the feet they need to survive. Human interference (ie. shoes) is typically not required except in very particular circumstances and/or with certain horses.