Passports are brilliant, as they are very personal and the child get's to help make it, so it includes the things that are really important to them.
There are a few examples on the net, which annoyingly, I can't seem to find at the moment but this pdf is a good introduction to how they work and can be used.
Ds's was initially created between him and the EP he was working with at the time and uses Super Mario characters as a theme to make it more interesting and appropriate to his interests. It talks about what things he likes and dislikes about school, what he finds hard and what he enjoys and is good at and what sort of things worry him and make him anxious, as well as his physical limitations. It also gives some background to his life, that he has a younger brother and sister, pet dogs and his main obsessions interests so that teachers etc can easily find something to talk to him about, iyswim. Finally it outlines what his coping strategies are, where and to who he will go for help and what he needs in the way of support when he is upset or anxious. Some children like to include photos of themselves, their family, their toys, pets and home etc as well.
Another idea I've loved recently was the one from Coff33's thread about her ds's new primary school, where they encouraged him to take photos of the new classroom and teachers and put together a scrapbook with them. I love this idea for him being able to refer back to it across the summer and familiarise himself with where everything is in his new class and how everything looks etc, so it doesn't all seem so new and scary come September.
I would also suggest introducing him gradually to the teacher before he breaks up for the summer, so that he knows her and doesn't see her as someone completely new and unexpected in the new term. Similarly, if he could spend some time with next year's class TA before the term is out he might feel he has an ally in him/her.