In addition to this, I was thinking since some retailers offer a completion discount it may be worth it to load up your registry with essentials.
This is what I was thinking. I'm going to add everything to mine, mark things are purchased like PP's have said, and use the completion coupon to finish up after my showers! :)
But if you already have everything, I don't think a small registry is a bad thing. Especially if you're not having a huge shower.