I started using teacher stamps about 7 years ago. The first self-inking stamp I got was a cute ladybird with a thumb up, saying "Super!". I use it to mark homework in the primary grades. It's a kind of a reward for those who do homework. But then I had to figure out how to "punish" those who don't do homework and to convince them to finish it. That's why I got another self-inking stamp, saying "No homework. Please finish it.". It's in Polish, so the parents can understand.
My students are used to the stamps, and they are happy to get the "Super" one.
This year I needed something to motivate my 2nd-grade students to behave well during classes. I bought two new self-inking stamps. After each lesson childern's behaviour is assessed and they get either "Like" or "Dislike". In this way all of the students who behave well are rewarded, and the troublemakers are punished.
Recently I have bought online wooden stamp set, but I haven't used it yet. I'm a bit dissapointed, as the stamps are rather small. Who knows, maybe the children will like them.