(P.S. In the picture above, the triangle to the left of the icons means that the application is currently running.)

From top to bottom:

1. Finder, the ubiquitous Mac equivalent to Windows explorer, it’s not as nice or flexible, but it’s slick enough.
2. Transmission, the sweet little Bittorrent client that’s easy on a Mac. I used it’s equivalent uTorrent on Windows since the one thing I hate most is bloated software. It works well enough, but it still chokes on some torrents, and it’s not as compatible as I’d like.
3. Download Wizard; after searching high and low for a Flashget replacement and coming by the way of Speed Download, which appears to be the most advertized, I liked the small footprint of Download Wizard. It’s still not a Universal application, which means it feels sluggish and takes ages to load, but it does it job real fine.
4. Firefox, the ubiquitous browser. Having said that, replacements for the Mac are amazingly good, and the only thing stopping me from using Safari (or better yet, Shiira or Camino) is the extensibilty that’s built into the fox. Minor annoyances: no spell-check as in most native Mac applications, no support for the built-in password management tool.
5. Terminal, an adequate Unix Terminal (but not the best I’ve used), it launches instantly and stays out of the way. No tabs, and no support for Pg-down/Pg-up in man pages (which I think can be fixed by some hacking) and no color codes.
6. Textmate. The single greatest editor I’ve used on any platform. This makes editing my PHP (and now, Rails) projects fast and a no-brainer. It really stays out of your face and allows you to think in code. Emacs + OSX nirvana!
7. Netnewswire Lite, the fix for the news junkie. It fetches RSS feeds from any number of sources and displays them intuitively and with minimum of fuss. There’s a pro version, but the lite is more than enough for my needs.
8. Itunes, the Mac audio player. I still haven’t got used to its “convention over configuration” arrangement, but it’s surprisingly easy to get started, and arranges all my music pretty well on the disc. I use it mostly for accessing my Ipod nowadays since I’ve not yet selected the tracks I want on my mini. When it plays music, it stays out of the way.
9. Preview, the default Mac application for “opening everything”. It serves as a really good PDF reader, image viewer, etc. (No automatic viewing in directories, view the next file, etc. but it suffices).
10. Quicksilver, this isn’t shown here, because I’ve disabled the dock icon, but Quicksilver is the GUI application for console lovers :-). An oxymoronic description, I know, but it’s true. It’s a text-launcher on steroids.

Note that I run all these simultaneously on my Mac mini with 512M ram. Aye, I badly need more like when I’m in the process of designing something I’ve got Photoshop+Omnigraffle+Dreamweaver open, or when Netbeans+Tomcat chokes up my Java development, but for the most part, it runs fine. The spinwheel is my friend.