I love reading the book Chrysanthemum by Kevin Henkes on the first day of school. When I taught first grade, I spent more time on the concept of names (letters and sounds), but now that I teach second grade, we spend a lot of time on what it means to be a good friend as well.
Some fun activities:
1. Letter bead necklaces: I found great foam letter beads at Michaels and my students loved making name necklaces. It also helped me learn their names quickly!
2. Name Graph: Count the letters in first names to make a class graph (Chrysanthemum has 13 - we usually include her in the graph)
3. ABC order: Students line up in alphabetical order with name cards
4. Word Wall: I usually add students' names to the word wall - there are so many things you can do depending on the names in your class. (i.e. Gillian/ Greg, Cecilia/ Chris/ Cara, Sara/ Shawn, Will/Bill, Ry-an/ Re-bec-ca, Edgar/Ethan...)
5. For "homework" I send home a sheet that has questions for students to fill out with their parents about how/ why they got their name
6. I often use this book as a lead in to talking about class rules/ responsibilities. We talk about how Chrysanthemum's feelings changed throughout the story and why, which leads into what we can do to make sure everyone is happy and able to learn each day. This is also a time when I have thought about doing a sequencing activity either with pictures or sentences - in response to how did Chrysanthemum's feelings change during the story.
7. Paint names on a large piece of construction paper/ and or a self-portrait (I know paint is bold for the first day of school so you may want to use crayons and other art supplies instead).
I'm sure there are so many other ideas out there as well!