Adium

Multi-protocol Chat client that supports all the major services (Google, Yahoo, AIM, Hotmail, ICQ). Sports a great UI, supports Growl notification, lot of nice themes/templaets for chat window. Based on libGaim so suffers from the same lack of YMSG over HTTP support (which means Yahoo may not work if you are behind a corporate firewall).

Alternatives: Fire, Proteus

CyberDuck

FTP and SFTP client/browser with support for Rendezvous/Bonjour. Provides bookmarking for frequently visited sites and synchronization with remote sites. Also supports resumption of transfers.

Alternatives: Fugu, Fetch[$], Transmit[$], RBrowser, Interarchy[$]

Desktop Manager

Expose is nice but as any Unix-head will tell you a Windowing system is nothing without a Virtual Window Manager, and that’s where Desktop Manager comes in. Use your single physical screen as multiple virtual screens with neat transition effects, a desktop pager that can auto-hide, configurable shortcuts, and the ability to move windows across virtual screens and even make them sticky on all screens. The biggest drawback is the lack of a way to denote certain apps as always sticky At least an easier way should exist (such as a graphical button in the application titlebar) to make it sticky.

Alternatives: Virtue

Ecto

Ecto is a multi-platform blogging client that supports a wide range of Blog servers and services (WordPress, Blogger, MovabeType, LiveJournal, etc). The UI is straightforward, the rich-text editor provides a good idea of the final look and feel, and there are some additional goodies such as inserting links from Amazon search. Ecto is not free, however.

Alternatives: Qumana, Bleezer, Xjournal, MarsEdit[$]

FireFox

Unarguably the best web browser available! ;-) Tabbed browsing, fine-tuned privacy (cookies, forms, etc), zillions of extensions, and that’s about 1% of the available features. Forget that old notion that a Mac is best used with the inbuilt tools. Safari is no substitute for a real web browser.

Alternatives: Camino, Mozilla, Opera, OmniWeb[$]

Growl

Growl is a notification system that provides other applications the means to notify the user of events. Various applications (including many listed here, such as Adium) support Growl notification. Notifications are customizable.

Also See: GrowlTunes, HardwareGrowler, NetGrowler

iEatBrainz

CDDB etc are nice if you are playing, ripping or storing albums, but what about individual songs? For that you need the MusicBrainz service. And iEatBrainz is a client that lets you tag your iTunes collection (AAC or MP3) using acoustic matching from MusicBrainz.

iTerm

Terminal.App is for babies. iTerm adds the features that any Unixhead used to KDE/Gnome absolutely needs. For example: tabs for multiple remote terms. X style cut and paste. And a few other nice features.

NeoOffice

OpenOffice.org based office application suite that can read and write Microsoft Office files (Word, PowerPoint, Excel). Its a bit slow and sometimes has problems with advanced formats in MS files, but does the job for the 90th percentile.

Alternatives: OpenOffice.org

Quicksilver

A launcher with an amazing number of features. Launch applications, visit bookmarks, setup custom shortcuts, open files, all with simple key shortcuts.

Alternatives: Butler

Taco HTML Edit

A neat HTML editor that provides the basic set of features that makes it useful. Others like n|vu provide better WYSIWYG support but make it surprisingly more difficult to edit a page (such as by fixing table and cell widths, to use a random example). Taco provides a Live Preview that suffices to see what your HTML looks like. It also enables quick insertion of tags, performs syntax highlighting, etc.

Alternatives: n|vu

Thunderbird

If Safari is inadequate compared to Firefox, Mail.app is a joke compared to Thunderbird. The list of features in T’Bird requires a separate web page altogether, but here are a few: multiple accounts with multiple identities, filtering, searching, labelling, Virtual Folders, LDAP addressbook, GPG (Enigmail), message aging, etc.

Vienna

RSS newsreader with inbuilt page viewer, tabs support, categories (including dynamic “smart folders” defined using filters — very useful for deleting those pesky “Open Threads” ;-)). One feature that would be nice is OPML synchronization with a service like Bloglines.

Alternatives: BlogBridge, Feed, Jager, Lektora, , NetNewsWire[$], NewsMac, PulpFiction, Strider[$], Bloglines, NewsGator, Shrook, Gritwire, and various other online news aggregators (Yahoo, Google, FeedLounge[$], etc).

• Eavesdrop: packet sniffer
• Saft add-on for Safari
• Screen Spanning Doctor: MacOS support for screen resolution limits it to the highest available on your iBook/PowerBook, though it can support higher resolutions, such as on an external monitor. Screen Spanning Doctor helps you not only extend your screen to an external monitor, but also helps support the higher resolution.

• A nice Podcast client. At least for me, iTunes, iPodder, etc do not cut it.
• If you do not have Tiger and want something similar to Dashboard try Konfabulator or KeepAnEye
• Better LDAP support in the AddressBook. Currently subscribing to external directories is a crapshoot — it may work, it may not!