Different Horse Coat Colors

Have a horse auction in game that allows you to buy and sell your horse.

 

I'd love the option to be able to own more than one horse, really. Build multiple stables, choose from a variety of colors, and maybe have more interactive choices with the horse other than riding. Feeding it treats, brushing it, etc. There's a lot that could be done with the horse to take it beyond just being a method of transportation.