I second that. The Republic Commando novels are basically Mandalorian novels, she developed the language, history and culture pretty much all by herself and generally as a background to her Commando novels. They are trained by Mandalorians and instilled with their values etc. It's very in-depth, I really recommend them.
I don't know if comics are your thing, but there are plenty of appearances there too- plus the Mandalorians have featured entire episodes in the Clone Wars animated series. The Death Watch are becoming more and more essential to the plot- it's now on series 5 I think, and I'm sure the True Mandalorians under Jaster Mereel will have to come to power soon.