Welcome to www.dtracebook.com! This website supports the book:
DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X, and FreeBSD by Brendan Gregg and Jim Mauro, Prentice Hall 2011
On this website you'll find the scripts from the book, additional versions of those scripts, book errata, and links to other online resources. A tarball of all scripts has been made available by Mike Harsch. You can also download the full TOC and sample chapter (File Systems).