Most interesting in System Optimization

Free
Provides MacOS users a way to run X Window applications.
It is designed for mutiple audio tasks:record live performances.
A program for monitoring your Wi-Fi network strength.
Free
Magican helps you improve the performance of your Mac.
It delivers hardware diagnostics, drive repair and daily maintenance.

Top rated in System Optimization

Drive Alert
Free

Drive Alert will warn you about imminent hard drive failures on your Mac system.

FlareFighter
Free

FlareFighter lets you pause the Flash plug-in where you are not using it.

SixtyFour
Free

A memory optimizer that opens 64-bit apps in a 32-bit mode.

More Memory
Free

Take control over your RAM usage. Have a slow Mac? Don't want to take the time to restart?

Flush Memory
Free

Must-have tool that will free up RAM on your computer.

iconXprit

Manage custom icons when working with Finder.

Purge
Free

Purge is the first free RAM optimizer for Mac OS X.

Appsolete
Free

Appsolete is a nice system utility that can help in your switch to OS X Lion.

Purger King
Free

Purger King is the strongest and simplest memory cleaner.

SteelSeries ExactMouse Tool
Free

The SteelSeries ExactMouse Tool provides a more natural mouse-movement, increasing precision and improving gaming performance.

PingBar
Free

This application pings your server periodically and shows you the delay.

MacInside
Free

It contains information about processes and application running on your Mac.

Startupizer 2
Free

This app helps you manage login items on your Mac.

UpdateMenu
Free

It is a program that keeps your applications up-to date.

Witch
Free

Switch between windows or programs with customized options.

Exhaust
Free

Exhaust allows you to manage your login items in a very simple manner.

Deskovery
Free

Change the size and position of your desktop windows.

MiStat
Free

Monitor and control the condition of your Mac.

PseudoAnacron
Free

OS X does some periodic maintenance tasks at specific times.

SpeedTools Utilities
Free

A collection of utilities for system optimization.