Setting up an LVM cache on an SSD can supercharge LVM.
Fibonacci Hashing: The Optimization that the World Forgot (or: a Better Alternative to Integer Modulo)
A utility that works like the top utility of Unix machines, only it watches MySQL threads to tell you what they're doing and how busy they are. Useful for figuring out where your apps are bogging down.
A list of tricks and methods for optimizing code written for the ATmel microcontrollers using GNU GCC.
A Perl script that logs into a MySQL database server (with or without credentials), analyzes it, and makes suggestions to optimize its performance.
A utility that uninstalls all of the cruft from Windows that turns it into a 15 gigabyte disk hog right off the DVD.