I always wear a kilt pin with my trad kilts, but never with my moderns.
Speaking of kilt pins, I had recently commissioned a Bee pin/brooch thingy from a fantastic artist up in Seattle. He's made primarily from old watch parts. I love the little guy, but he's just a tad to heavy to wear on a shirt or vest. I think I know what to use as a kilt pin in Reno!
Here's a piccie.