I plan to leave up my Christmas items year round, like someone said it could be a way to bring someone into your shop. Even if it's not exactly what they are looking for, they may like the design and want to see more of what you do!
Carmel - There is no way to do that that I know of, but you can add a listing for gift wrap to your shop, just make it clear if someone buys just the wrap from you and nothing else, they will get the gift wrap you would wrap an order in (and anything else you offer, think - bows, ribbon, cards etc.) folded in an envelope and nothing else. Also be sure to list it as a supply unless you make all of it yourself, wrapping a box doesn't count as handmade per Etsy guidelines.