Below are my most used Application List in Mac:1. jEdit
Actually I have tried many editors, including Textmate, TextWrangler, BBedit, Smultron. But I settled with jEdit for its powerful plugins, including sftp support (which is a must for me), customizable and extensive syntax highlighting support and customizable keyboard shortcuts.Another big reason is its multi-platform support. It's a very painful experience to use another editor whenever you need to change OS environment. As jEdit is in Java, it can be run in Windows, Mac and Linux.
2. iTermA great alternative to Terminal. As compared with Terminal, it has multiple tabs, and fast shortcut to bookmarks. Previously versions of iTerm has problem of screen refresh slow down when a session is opened for a long time. Recent versions has fixed this and quickly become my favorite app. (Well, note that starting from Leopard, Terminal will also have tabs. Wow!)
3. muCommanderA great sftp/ftp application. Another cross-platform application. Beside sftp and ftp, it also support SMB and http. One of its killer feature is, you can perform file transfer across different servers directly, no special requirements on the remote servers! (as opposed to some ftp programs in Windows in order to achieve this). Though you can only have 2 columns opened for 2 servers in one window, you can create more windows of this app and connect to more servers. Files can be drag and drop across diff. windows (and hence different servers!). Another feature I like is its keyboard oriented navigation, which allows me not to touch the mouse at all.
4. VLCA great media player which support huge list of video formats. It can be a great alternative as a music player also. One thing I don't like iTunes is that it force you to add the music files to its library before they can be played. But not every music file (mp3 etc) you would eager to add to the library. For this case, I willl drag the files to VLC.
5. CotVNC (Chicken of VNC)
Best VNC client in Mac. It even supports Bonjour to discover VNC servers in LAN. Together with ssh tunnelling (using ssh command), I can perform VNC connection to many remote PC/Mac behind firewalls. Oh, for Mac VNC server, you can try Vine Server (Vine)6. Parallels
I don't think I need to tell you what it is. Actually I think it is a killer application for Mac, which drives many people to use Mac hardwares. Being a programmer, Parallels allow me to run a Ubuntu server inside Mac, not to mention to use IE7 for testing web page layouts.7. Skype
For video conferencing, I think the quality (especially voice) is even better than iChat.8. Thunderbird
Add-ons support and more fine-tuned settings is why I keep using Thunderbird instead of Apple Mail. Besides, it's also a good RSS Reader and newsgroup reader too.9. NeoOffice
You can also try OpenOffice. But NeoOffice offers a much better Mac user experience.10. QuckSilver
Hands down the killer app. for Mac. Apple Spotlight even not comes close. You won't believe you can do so many things with your keyboard.11. Journler
If you look for well categorized notes application, this is it. But it can do much more than that. It has Smart Folder, tags, super fast keyword search, blog support, iLife support, embbeded browser..... If you know how to sync its data files to multiple Macs, then your essential information/notes/ideas is always with you.12. Camino, Firefox, Netscape, Opera, Flock
You may not believe me. But I do use All of them. Each serves its own purpose, and has its own strength for different purposes. Camino is a fast, mac oriented UI and mozilla rending engine browser. Firefox provides huge of addons, and hands down the best browser. Netscape (only v9 or later!) provides a fine-tuned firefox experience, it feels a little bit faster (at least for start-up) and add some good tools by default. Opera is the fastest browser, plus you can use it for BT too. Flock provides great integration with Flickr (and other photo services) , blogs, bookmarks services. It's also mozilla based too.You should try every of them to see which one suits your needs most.