How does your Business School show appreciation towards guest lecturers?

I observed here at Queen's School of Business that they have a nice, little ritual to show their appreciation to guest lecturers who have taken their time to come to the school and share some of their knowledge with us. At the end of the class, one of the students hands the guest a nicely wrapped box (probably chocolate) and thanks for their trouble.
Pretty simple, sure. But nice anyway. The "Financing New Ventures" course I am taken uses guest lecturers a lot, and all 4 who have come so far have been extremely helpful and open, their experience truly invaluable.
Pictured above our main lecture room, Goodes Hall 410. Although people leave their name signs on their customary places, these places are changeable.