Ever try to explain what an Etsy Team is to someone, and wish you had something to give them so they'd remember your conversation? Just like promoting your shop, having a little something for someone to walk away with can jog their memory and make your marketing more effective.
Business cards or stickers can be relatively inexpensive, especially when multiple team members split the cost. You can include your team's name and a little blurb about what you do. If you're a local team, maybe include something about the importance of supporting local artists. For a global team, you may want to include what all of your shops have in common - like a common medium or cause. You can also include any search phrases or tags your team uses, along with a blog URL, a flickr pool address or other sites of interest.
Make sure your promotional items are easy to read and really pop - people are more likely to keep and use something that looks really good! You can even hold a design challenge, like the Etsy Glass Team did, before you order cards. Once your promos are made and arrive, everyone on the team can take a big ol' stack to hand out when they're talking up Etsy, or to include in packages they ship out from their shops.
For stickers, business cards or other promos, browse on Etsy or check out the forums for recommendations from other sellers on where to get promos made.