This was posted by PeterHanson in the Forum Question thread, and I was afraid it would get lost in the shuffle, so am reposting it here, in case anyone can help.

Hi, I got a crestie about a month ago and he's doing great but, today i accidentally shut the end of his tail in the door of his cage. (i felt really really bad and apologized over and over again in tears) he didn't drop it though.
i was wondering if there is anything i could do for him? the area that got hit has gotten shiny. a little bit of skin peeled off on one side but there isn't any blood of fluid coming out of any kind. also the area after the shiny part has gotten slightly darker and the pattern is now misaligned with the rest of his tail. if you know of anything i could door for my friend i would love to hear from you! Thank you!
It may just be bruised; watch for swelling, oozing, or any kind of infection...if that happens, get him to a vet so any infection doesn't spread. He may or may not lose the tail. Don't beat yourself up over it; accidents happen, and from now on you will be very careful about closing the door. I hope your gecko will be fine.