GeekTool - Freeware
GeekTool is a PrefPane (System Preferences module) that lets you display information from command-line applications on your desktop
Requirements: OS X 10.5 or later
Growl - Freeware
Growl is a notification system that allows any application to send it a notification, and then it displays it. You can (for example) be notified that you have new email, or that a download completed, etc.
Requirements: OS X 10.5 or later, 10.4.11, or 10.3.9 (see compatibility notes)
iStat Menus - Freeware
iStat Menus lets you monitor your system right from the menubar. Included are 8 menu extras that let you monitor every aspect of your system: "CPU," "Memory," "Disks," "Network," "Temperatures," "Fans," "Bluetooth" and "Date & Time"
Requirements: OS X 10.5 or later
MenuMeters - Freeware
MenuMeters is a set of CPU, memory, disk, and network monitoring tools for Mac OS X.
The MenuMeters monitors are true SystemUIServer plugins (also known as Menu Extras). This means they can be reordered using command-drag and remember their positions in the menubar across logins and restarts.
Requirements: OS X 10.2-10.5.8.
(10.6.x compatibility added in the v1.4 beta)
NTFS Mounter - Freeware
A simple utility designed to mount NTFS volumes in read/write mode. Although not officially supported, Snow Leopard is now able to mount NTFS volumes with both read and write support. NTFS Mounter simply uses this ability, and provides a simple user interface to the mount command for NTFS volumes.
Requirements: OS X 10.6 or later
SmartSleep - Freeware
SmartSleep.prefPane lets you select each sleep state. Additionally the new SmartSleep state lets your notebook just sleep while the battery has a high level. If the battery level drops below a certain point (default is less then 20% or 20 minutes) it will switch to sleep and hibernate. So you have the best of both worlds.
Requirements: Mac OS X 10.4.1 or later
32- or 64-bit Kernel Startup Mode Selector - Donationware
Mac OS X 10.6 Snow Leopard is both 32-bit and 64-bit, and what that means for you depends on both your hardware and your settings. This application: shows whether you have a 32-bit or a 64-bit processor, shows whether you have a 32-bit or a 64-bit EFI,shows whether the MacOS X Kernel is set to boot in 32-bit or in 64-bit mode, shows whether the MacOS X Kernel is running in 32-bit or in 64-bit mode,shows whether Apple officially supports booting a 64-bit kernel on your Mac and allows you to select whether you want to start the MacOS X Kernel in 32-bit or in 64-bit mode (the setting might be ignored on MacBooks, depending on how Apple implements the restriction)
Requirements: OS X 10.6 and later
teleport - Freeware
teleport is a simple prefpane utility to let you use one single mouse and keyboard to control several of your Macs. Simply reach the edge of your screen, and your mouse teleports to your other Mac! The pasteboard can even be synchronized between the computers.
Requirements: OS X 10.5 or later; Intel processor