If you shop at Swiss Coop (Coop City or regular Coops, not at Pronto) a lot, sometimes the cashier will ask (very quietly in my experience) if you want "Merkli" -- these are the stickers to collect. For every 10 CHF you spend, you get one sticker (or if you buy a lot >200 CHF and the cashier is feeling generous, you might get a few more than 20). Sometimes, You need to be proactive and remember to ask for them after you've finished paying (but before leaving!). "Merkli, bitte" usually works. You'll see the little handout flyers at the checkout as well.
Disclaimer: I am not sure if the term, Merkli is Swiss German and/or only used in Basel!
The current offer is for pots and pans. If your German is good, see here.
http://www.coop.ch/pb/site/common/no...Lde/index.html
Coop doesn't always have a "Trophy" offer on, and sometimes they are not so useful for all people. Last time it was wine glasses and such, and for me, we already had plenty, but collected the stickers anyway because we are weird.

No, uh, really because we know people who could use nice wine glasses. Sometimes if we know a wedding is coming up, this gives us a chance to get something nice without really breaking the bank, and it's fun.
Furthermore, the stickers only cover part of the actual cost of the full retail price of the item. But usually it is high quality stuff so a 30 - 50% discount is quite acceptable to most. It is not cheap by any standards. But it's a nice to have.
It's like Migros Domino Mania (I first thought it was only for kids). If you have a Coop Card too, you can get points that way for other stuff. That I find is more useful than the Merkli seasonal offers.