The dollar dance is a touchy subject. Unlike most of the other items on the list, it's actually a well-established and venerable tradition in many cultures. It's also got a practical side -- weddings often have price tags equivalent to a semester at an Ivy League college. Every little bit of extra cash helps.
Guests have already traveled (in some cases ridiculous distances); rented rooms, cars and cummerbunds; bought the electric potato peeler from the registry and cried their eyes out during the ceremony. After all that, pinning cash to two people who have just pledged to be with each other forever can feel a little, well, vulgar, especially if you don't know the bride or groom all that well. Instead, how about we write the bride and groom a check and leave it on the table next to the many, many bottles of wine we've emptied over the course of the night?