Perhaps you could put holes in the four corners and tie them together to make a shopping bag, like you may have seen with juice cartons.

You could offer them on your corporate website. there may be people who couldn’t attend but would still like to get a sticker.

If its possible, you could cut off the date part, and put them on folders so that you’ll have some for employee use, and free advertisement.

This woman takes vinyl stickers and banners and makes bags, laundry hampers, door curtains, and portfolios out of them:

http://www.jennyhurth.com/home-new.html

If you are sending future communications to the conference attendees (such as a feedback form, or a reminder note to book ahead for next year’s conference), you could insert the sticker as a “souvenir” - a “gift” to stick on their car or whatever. If you have a group photo of the attendees, I would also put this in the letter, even if it’s a black and white shot - people love to feel they’re part of a group. To insert a sticker into each envelopes shouldn’t cost any extra postage.

If you’re a crafty person, or have/know kids who like to be creative, you can paint over the front of the sticker (with primer or housepain, perhaps?) and draw/paint/collage/decoupage on them and/or cut them into different shapes to make your own unique stickers, gift tags, bumper stickers, luggage tags, etc. Alternatively, use them instead of tape to hold things together (cut them into strips if they’re big enough).

I have used stickers in place of strong tape to close packages - perhaps you could use them for some company mailing.

Cut them into pieces and use them as tape! Or, as the previous poster suggested, you could use them for packing tape. If your company doesn’t want them, offer them to someone who is moving and needs tape to close their moving boxes.

They’re great for putting around seams in heating duct.