The PDF version of the classic MIT 6.001 computer science textbook Structure and Interpretation of Computer Programs (SICP), 2nd ed. by Abelson, Sussman & Sussman just got better.
The typography has been modernized for better on-screen legibility and comfort. All the mathematics is set in proper TEX, and figures redrawn in vector graphics.
It is an improvement of the Unofficial Texinfo Format (UTF) which was converted from the original MIT Press full text release by Lytha Ayth and maintained by Neil Van Dyke.
You can learn more about the new ebook, use the source, or read the PDF.