How do you thank a client after the deal is signed?

What are some ways you show your appreciation to a client after they've worked hard to get a deal done? Do you have a great "thank you for your business" email? Do you send a gift like a book or bottle of wine? A Cameo? Please share your ideas!

This question is geared towards deals following a longer sales cycle (e.g. Proof of Value, Business Assessment, numerous teams involved). They've put their reputation on the line and worked hard to get this done.