I've always loved UMPC's/little arm linux PDA's, and wanted to make one of my own for years, but I've always gotten stuck on the case.
Today, when chatting with a student about unrelated things, he suggested gutting a book, putting in a Pi, an LCD and a keyboard.
The only thing left for me to decide on was the book.
May I suggest The Hitchhiker's Guide to the Galaxy? Love this idea, can't wait to see what comes of it.