Most of these recommendations are for system utilities, to modify features or include features that are not present in a default installation of Mac OS X. Other recommendations are for application alternatives to what is included with a default Mac OS X installation (iTunes, Journal, Safari, Finder).

Play

Play is an application for playing and managing audio files. Play currently supports playback of FLAC, Ogg Vorbis, Musepack, WavPack, Monkey's Audio, AAC, Apple Lossless, MP3 and various other audio file formats. ecto Similar to BlogJet or Windows Live Writer in the Windows world, ecto is a blogging client for supporting Blogger, Blojsom, Drupal, MovableType, Nucleus, SquareSpace, TypePad, WordPress, and more.

TranslateIt!

TranslateIt! is a real time system wide translator. Just hover the pointer over an unfamiliar word (in any Cocoa Application), and you will see its translation in a pop-up window. Instantly.

AppCleaner

AppCleaner is an alternative to Add / Remove Programs from Windows. It includes separate tabs for Applications, Widgets, and other options. Unlike other similar programs, AppCleaner searches for left over files in your OS X installation.

AllBookmarks

AllBookmarks adds a new item to your Mac OS X menu bar giving you quick access to all your bookmarks. All your Safari, Firefox and Flock bookmarks are shown and can be selected.

macam

macam is a driver for USB web cams on Mac OS X. It allows hundreds of USB web cams to be used by many Mac OS X video-aware applications. The aim is to support as many web cams as possible.

TigerLaunch

This is a great little launcher since there is very little space or customization ability within the dock. It displays an Apps menu at the top of your screen listing all your applications in alphabetical order no matter what folder they appear in. You can easily configure it to exclude applications you rarely or never launch.

Macintosh Explorer

Mac Explorer is a great alternative to Finder, for those of us that are used to Windows Explorer. It includes tabs, photo previewing, hierarchical overview of all files and folders, and more.

OnyX

OnyX is a multifunction utility for Mac OS X (PowerPC and Intel). It allows you to verify the Startup Disk and the structure of its System files, to run misc tasks of system maintenance, to configure the hidden parameters of the Finder, Dock and of some of Apple's own applications, to delete caches, to remove a certain number of files and folders that may become cumbersome and more.

Firefox

Of course I would recommend Firefox for any operating system (Windows, Mac, Linux). For Mac OS X, Firefox is a better alternative to Apple Safari for internet browsing.

City of Rauma

City of Rauma is an open source adaption of Sim City. It is inspired by the town of Rauma in Finland.

Adium

Since there is yet an official version of Trillian for Mac OS X (Trillian Astra X is in alpha testing), Adium is the most profolic solution. Adium handles Yahoo, MSN, AOL, ICQ, and more as a multi-chat client.

VirtueDesktops

VirtueDesktops is a virtual desktop manager for featuring, eye candy and configurable options that no other desktop manager on the mac has added yet.