The example of John de Goes' Haskell's Type Classes: We Can Do Better written in Scala.
It is precisely to allow for multiple type class implementations that Scala uses implicits to implement them. So I thought it would be interesting to compare Scala and Haskell here.
Discussion on HN
object MonoidInt{
implicit val MonoidPlus = new Monoid[Int] {
def empty = 0
def append(v1: Int, v2: Int) = v1 + v2
}