I've heard it many times "but he's just bay / chestnut / sorrel / brown"
Mostly from non-horse people, I admit. I guess from an overdose of Black Beauty and White Stallion :P
Myself, I consider bay, sorrel and browns are beautiful colours and they hide so much variety under such simple names! There are dozens of shades.
I'll list here some of my most favorite of these so called "boring" colors. Some are actually pictures of your own horsies, this forum has an endless resource of beautiful pictures. Please add more! :)
This type of bay - > no idea what its called officially. I love the lighter and darker dance of shades all over the horse's body. Makes it look like he's soaked in satin and velvet. And such beautiful reflection of light!

(photo owner: Lintu)
This type of sorrel looks to me like melted caramel. Combine it with some white socks, a flowing mane or a nice face marking and you got a beauty!

(photo owner: PaintsPwn)
I also like this type of bay, where the body colour contrasts strongly with the black mane and legs.

And also this deep red is beautiful. That's how I imagined Ginger would be, from Anna Sewel's novel when I was a kid :)

So post your "ordinary colored" beauties please!