I have developed a little tool in C# to automatically download comic-strips from XKCD.com (and in future from others) and generate it to a pdf-picture-book. Because i won´t have time in the next few months i have uploaded the prject to codeplex.com and added a open source licence.
If anyone likes to continue working on the code i appreciate it ;-)
If anyone likes a ebook with all xkcd-strips in it, feel free to try my tool :-)
Link:
http://picturebookcreator.codeplex.com/
Impression: