Get more feedback after your auctions and return customers by including your contact information when shipping eBay items. Here are some great sets of designs for custom eBay Business Cards. If you are a high volumn power seller who runs their own store and sells items that may have a lot of return customers and repeat business then you want to make sure they know how to find you again.
Offer a coupon code or discount for your auctions:
People don't bother to bookmark or save their auction history and if it's past the 60 or 90 days that eBay shows on their reports a person may not be able to remember who they purchased something from before. If you include a business card, it's likey they may save that and use it for future purchases. Plus if you have a website where you sell good direct and offer a slight discount, this is a way to cross promote that as well.
Vertical fashion or clothing shop:
Offer a reward program for repurchasing:
Vintage or antique store: