All the Pine Hollow ponies are named after small change. I couldn't find much infomation about them but here is a little bit about the ponies from the show.
Dime: is a very tempremental pony with a shaggy mane. He pins back his ears when he is upset and he likes to throw his riders off at least three times a week. He is also very attatched to Penny.
Penny: is a very sweet natured mare and she is very attatched to Dime.
Nickel: is a gray mare.
Eddie: is a fat brown and white pony and is very naughty!
In the book other ponies are mentioned now and then but not with very big descriptions. I remember reading that there was one pony called Half Dollar, but who would call a pony that!