B) A favorite children's book!
Many parents feel anxious over "no gifts" birthday parties, feeling unsure whether it's really OK to not bring a gift. While I feel it is perfectly fine to honor the party host's request, a great alternative to showing up empty handed is a gift of a favorite children's book.
Children's books are my gift of choice for many occasions, and a child's birthday is a great time to add to the birthday boy or girl's reading materials. There are many wonderful books available, and birthdays are a great time to choose something special, like a beautiful pop-up book, a book with great illustrations, or one of your family's special favorites.
Need inspiration to help find the perfect book for a birthday gift? Consider the birthday child's interests, and check online for some great kids' books blogs and Web sites. Have fun!
UPDATE: Here's another great option for a no-gift party -- a musical greeting card. They are a lot of fun!