This is just awful. I read up on missing children on Websleuths, a forum dedicated to tracking down the missing. Not sure if they have a post on this little girl there yet, but I will register there and post one if needed.
In the meantime, I think it'd be a good idea to send the girl's photo and info to everyone in our address books.

Neviaeh Amyah Buchanan
height: 3' 8"
weight: 45 lbs
brown hair and brown eyes
last seen: 8:15 p.m. Sunday, 1166 N. Macomb St. in Monroe; wearing a red, white and blue shirt and knee-length jeans; police found her bicycle in the parking lot of the Charlotte Arms Apartments.