http://dtrace.org/blogs/brendan/2011/10/10/top-10-dtrace-scripts-for-mac-os-x/

TL;DR from reddit:

iosnoop - This “traces” disk I/O execution live. Each time a disk I/O completes, a line of output is printed to summarize it, including process name and filename details

hfsslower.d - The hfsslower.d script measures I/O before it is processed by the HFS+ file system. (iosnoop measures I/O after the file system, and only if it reaches disk)

execsnoop - This prints a line for each new process that is executed, in a rolling output similar to the previous tools.

opensnoop - This traces file opens and prints various details

dtruss - The dtruss tool traces all types of system calls, like strace on linux.

socconnect_mac.d - traces outbound TCP connections along with details

errinfo - This tool provides a summary of which system calls were failing, showing the process name, error code, and short description of the error

bitesize.d - This is a simple DTrace script that characterizes the disk I/O workload, showing a distribution of the size of the I/O in bytes along with the application name:

iotop - presents the same data as iosnoop, but in a summarized way similar to top

maclife.d - traces the creation and deletion of files