I picked up these adorable Halloween nail decals from Sally a couple weeks ago. They're by Cina and the style is called Haunted Nights.
You get one sheet of decals with a bunch of designs accented by sparkling metallic gems. I guess they're not really true 'gems', but they are little chrome metallic dots that look like gems. There's a big white spiderweb with multicolor accents, some skull and crossbones designs, bats, ghosts, haunted houses, though oddly no pumpkins!
I haven't worn any of these yet, but I'm about to do a Halloween-themed mani, so these may make an appearance pretty soon...
Like I said, I got mine at Sally Beauty. I don't recall seeing these anywhere besides Sally.