I have been on a Mac since I started Content Here a little over a year ago. The migration for me has been an unqualified success. I won't go back. Here is a list of apps that have made the experience that much more pleasurable.
Mail, Calendar, Address Book: Mac Apps
I decided to go with the Mac defaults: Mail.app, iCal, and Address Book. Since these applications are pretty much always open, I wanted them to be stable, well integrated, lightweight, and just good enough. They work as advertised and I have absolutely no complaints.
When I started taking longer trips for client projects and conferences, I realized I needed an offline blogging tool. For a while I used a simple text editor and then copy paste into the Blogger web UI. Then I went to Ecto which I used for around a month until I got annoyed with its quirky notions about HTML. I bitched a little on the support forums to no effect and then decided to vote with my feet and went over to MarsEdit, which I love. It doesn't try to give you WYSIWYG editing features and that is OK by me.
Simple Editor: TextMate
I started out with TextWrangler because it's free. I tried TextMate because I like to be able to set up "projects." Before I discovered you could set up a "disk browser" in TextWrangler, I fell in like with TextMate. I seem to be in good company because I keep recognizing TextMate in screencasts.
I write my reports in XML (DocBook) so a good XML editor that validates as I type and runs my transforms is important to me. I was disappointed to learn that XMetaL doesn't work on the Mac. I bought oXygen. I first used the Eclipse plugin but then I transfered my license to the stand-alone version, which is a lot faster. I am pretty happy with it. It comes with the Syncro SVN Client which works well enough.
I rarely do serious coding anymore but when I do, I use Eclipse. Eclipse takes so long to load that it makes me think twice about whether I want to get sucked into my programming head and lose track of time for the next few hours.
Source Control: SVN via Wush and the Syncro SVN Client
Old habits are hard to break and I am a religious source control user for my website and my reports. Wush.net takes care of the Subversion hosting. Syncro is my client when I am not in a command line mood.
When I bought my Mac, I felt obligated to throw in a license for Microsoft Office. Big mistake. I thought I hated Office for Windows. The Mac version is worse. I am very happy with the iWork applications and tend to write deliverables and presentations in Pages and Keynote and then export to the Microsoft formats. It is a good thing when your office applications don't suck your will to live. I have NeoOffice installed for the occasional Open Document file I receive. It sure would be nice if iWork would support Open Document. Maybe if both MS Office and iWork supported it, ODF would realize its vision.
The one Windows application that I thought I was going to miss was Visio. Then I found OmniGraffle and I have moved on. Although there are not as many stencils as Visio, you can read and write from Visio's XML format with relatively good accuracy.
Image Capture: Command-Shift-4, Flickr, Skitch
For work I look at a lot of software and I take a lot of screenshots. Typically, I use the key command Command-Shift-4, then space to get a .png image of the active program saved to my desktop. Then I upload the files to Flickr and tag them appropriately. After doing that for about a year, I have a nice little library of screenshots that is organized by keyword. When I want to blog a picture immediately I tend to use Plasq software's Skitch because it lets me quickly post the picture with all my cheeky annotations.
I have absolutely no loyalties to any browser and I switch whenever the wind changes direction. Today I am using Firefox 3 because I wanted read my feeds offline with Google Gears. I think I like the Camino keyboard shortcuts the most though. I also like how Safari and Camino share a password database. For some reason I have been leaving Opera out of my rotation. I guess even fickleness has its limits.
Time management: OfficeTime
When you run your own business, you need to be very careful to manage your time efficiently. No one else is going to do it for you. In addition to keeping track of billable hours, I also track time for internal projects including research, reports, conferences, blogging, and general admin. OfficeTime is like a little stopwatch that you can start and stop when you work on different things. There are reports that tell you how you spent your time today, yesterday, this week, last week.... I find that tracking time in this way helps keep me focused on doing the important work and prevents me from task switching inefficiently. OfficeTime is not the prettiest application in the world but it works. I even like the sound effect of the clock ticking for a second when you start it. It gives a sense of urgency to get started on your task.
QuickBooks on a Mac is lame but my accountant uses QuickBooks so I am stuck with it. The Windows version (which my accountant uses) is totally different from the Mac version but I can export a Windows friendly "Accountant's Copy" of my "Company File" and I can translate his bookkeeping instructions to the Mac UI. I don't care enough about accounting software to switch even if there was a cooler Mac-oriented accounting package that could export a QuickBooks Company File to share with an accountant. For personal finances, I use Mint.
Project Planning: Concept Draw Planner
Usually having a white computer gets you out of being responsible for making Gantt charts. However, on the off chance that I need to put together a project Gantt chart, I use Concept Draw Planner. It's good enough.
Task Management: Things
I didn't like the changes to iCal's task feature that came with the Leopard upgrade so I started to use Things. I organize my work into "Areas of Responsibility" like "blogging," "household," and "research" and "Projects" a particular client project. Content entry is very quick and the "Next" view gives you a nice hit list of what to do when you have a free moment. Amazing piece of software. Try it!
I like Panic Software's Transmit.
Bit Torrent: Transmission
I am not saying that I use Bit Torrent but if I did, I would probably use a client like Transmission. :)
It just keeps on getting better.
Chat/IM: Adium and Skype
You can get me on pretty much all of the IM services as sggottlieb. Funny thing is that I have been using IM a lot less recently now that I use Twitter and Friendfeed.
When I am on IRC, I use Colloquy
I subscribe to a bunch of open source mailing lists and the best tool for that is Gmail. I really like the rules feature so I can automatically delete some messages (like a build failing) and tag messages by the open source project that they are from. I usually bulk read a project at a time to get caught up on what is going on.
My absolute favorite app isn't really an app. It is an app launcher: Quicksilver
Quicksilver is a program that runs in the background. When type Ctrl-Space, a little window pops up. I start typing and Quicksilver filters down its index of files and applications on my computer. For example, when I want to launch Camino, I hit Ctrl-space then "ca" and I see Camino. Then I hit enter and Camino launches. Or I type "web" and a bunch of files that have the word "web" in them pop-up including my slide presentation for WebContent2008. That reminds me. I have have to finish that presentation :).