The best book to follow up SICP is Essentials of Programming Languages, by Friedman, Wand, and Haynes. It uses Scheme to show how the fundamentals of programming languages are built, and both in its form and its content, it seems a direct continuation from SICP. After you've done with it, you'll have a much better understanding of Scheme, functional programming, programming languages, and programming in general.
I'm viewing it in Firefox, and the content area at the top is blank, while the sidebars ("What's this" etc.) appear. The content area (Command-line-fu alpha) appears all the way at the bottom, once all the sidebars finish.