I just bought an Apple PowerBook. So all you Mac users out there, email me your tips on the "must-have" apps/tools I need to download/buy and I'll post them here after a little while.
UPDATE (2004-09-18):
What people recommended (in no particular order).
Thanks to Simon Willison, Robert Fleming, Michael Twomey, Bill Anderson, Chris Adams, Ashley Aitken:
http://www.obdev.at/products/launchbar/
"if you prefer keyboard over mouse"
"having a fast search engine for apps, documents, contacts, etc. really changes the way you work."
"quick access to applications/URLs/email addresses"
http://www.mabasoft.com/downloads/worldClockDeluxeX.html
"for international travellers/workers like yourself"
"a more powerful version of the Dock for power users"
"a much better alternative to Apple's Terminal.app."
"replacement for terminal"
"(though I've temporarily reverted to Terminal.app for some stuff as I'm getting bad load issues with iTerm). For me it's terminal with tabs."
http://www.codingmonkeys.de/subethaedit/
"a fantastic text editor, and that's even before you start playing with the collaboration features."
"is collaborative editing as it should be. I know I've moaned about it in the past, but I still like it, and it's great for group editing."
http://quicksilver.blacktree.com/
"makes the Dock obsolete - an awesome way of launching programs and quickly finding files and contacts."
"having a fast search engine for apps, documents, contacts, etc. really changes the way you work."
"is a must (at least until spotlight arrives). Ctrl + space + first few letters of app's name = great way to launch stuff for people used to keeping an xterm around to launch apps."
"an open source video player, plays almost any format you throw at it (including DivX) and unlike QuickTime allows you to play things in full screen mode."
"Video file player"
http://www.ranchero.com/netnewswire
"an excellent RSS / Atom news aggregator."
"RSS client"
"THE news aggregator, just buy it (I know there is a lite, but just buy it)."
http://www.mozilla.org/products/firefox/
"Safari is good, but I find things like gmail work better on firefox. And type ahead find is hard to beat when you are addicted to it."
"it's a very user-oriented browser which relies on the Safari rendering engine."
"if you have a Bluetooth phone you can use this as a remote control for your computer (iTunes, PowerPoint, etc.) and to execute arbitrary commands based on state changes - pause the DVD player when you get a call, lock the screen or adjust IM status when you walk away from the computer, etc."
http://www.reelintelligence.com/BluePhoneMenu/
"completes things from a Bluetooth perspective - it manages your SMS history, maintains a call log, displays your addressbook entry for incoming calls along with options to reply w/SMS or punt the call to voice mail."
"this lets you remap keys and enable scroll-wheel emulation on a trackpad (I use function+trackpad for scrolling all the time)."
"remap keys/enable "scroll-wheel" like support w/ trackpad. I use in conjuction with sidetrack"
http://www.ragingmenace.com/software/sidetrack/index.html
"take full control of your trackpad"
http://www.apple.com/quicktime/products/broadcaster/
"allows you to stream / save arbitrary audio and video streams. I've used it for recording and streaming talks."
http://www.macosxlabs.org/rsyncx/rsyncx.html
"a resource-fork-aware version of rsync with a graphical front-end. I give it to portable users for backups since SSH works anywhere on the Internet and it's usable over slow connections."
http://www.bresink.de/osx/TinkerTool.html
"a front-end for a bunch of system customizations."
http://www.codefab.com/unsupported/
"an Aqua ssh-askpass equivalent. If you script SSH but don't use an SSH agent this will prompt you for your password."
"control outbound tcp connections"
http://www.ragingmenace.com/software/menumeters/
"a set of CPU, memory, disk, and network monitoring tools for MacOS X. (sit in toolbar)"
"is great for spotting runaway apps and generally getting a feel for your mac's status."
http://projects.tynsoe.org/en/geektool/
"is a geek's must have, it prints console messages (you know, the stuff which winds up in the syslog) in a discrete manner to your desktop. Great for spotting apps which are throwing wobblers (helped me pin down an odd issue with Control Center)."
http://wsmanager.sourceforge.net/
"gives you virtual desktops. I just have the menu bar desktops and drop the desktop panel myself."
"is an excellent blogging tool (I'm using it right now)."
http://www.mindlube.com/products/emacs/
"I almost didn't get my new job 'cos they thought I used vi (allegedly). Emacs is very nice once you've activated the pc-mode stuff, then you have sane selection and navigation."