These plates really do something for me. I would use them year-round. I think they would add a lot of drama to any event. I think most people would use them only for Halloween (which would almost be too expected, wouldn't it?), but I could see them used for tons of other events. I haven't picked up any Wedgwood basalt-ware yet, but it's another one of my current fixations (along with the aforementioned Old Paris porcelain).
Hop on over to eBay and bid on these plates.