I just went through the same thing.

Follow me on twitter as I explore the world of OSX and my adventures with all things "Hackintosh": @cericsmith

Here's my list:

1Password -- Perhaps the greatest piece of Mac OSX software. You must try to believe it. Password storage/sync/creation/ID management at its finest.

http://agilewebsolutions.com/products/1Password

Unison -- If Windows newsreaders hadn't stopped evolving around 1998, they might have come up with something like Unison in... 2150.

http://www.panic.com/unison/

MusicBrainz Picard -- For fixing the "Unknown Artist/Album" issues.

http://musicbrainz.org/doc/PicardDownload

BluePhone Elite -- Neat Smartphone/iPhone tricks with Bluetooth. Ever wanted to have your machine wake up or sleep when you were just out of range? This is an app for you.

http://mirasoftware.com/BPE2/

Toast Titanium 10 -- Sure, Leopard can burn discs... but Toast is much more than that, and it's elegance exceeds anything on Windows.

http://www.roxio.com/enu/products/toast/titanium/overview.ht...

iLife 09 -- iPhoto's face rec. is just cool, and iMovie beats the snot out of Movie Maker.

http://www.apple.com/ilife/

Stuffit Deluxe 2009 -- Not as necessary as it used to be, but still nice to have available.

http://my.smithmicro.com/mac/stuffit.html

Parallels 4 -- Many people like VMWare Fusion, but Parallels 4 has support for a lot more configuration of the VM -- support for up to 8 processors, the ability to have VM's start off of CD and/or Disk Image/ISO, is killer.

http://www.parallels.com/

Little Snitch -- knowing when your applications are "phoning home" is important.

http://www.obdev.at/products/littlesnitch/index.html

DiskWarrior -- HFS+ disk maintanance package and more. Fix disk errors...

http://www.alsoft.com/DiskWarrior/index.html

AppZapper -- Yes, theoretically uninstalling apps on the Mac is straight forward, but AppZaper gets all the flotsom and jetsom that would otherwise be left behind. Great for nuking preference files, etc.

http://www.appzapper.com/

ClamXav -- Ok, we know that Mac's don't get virii, per se... but this cross-platform, donation-ware AV tool gives peace of mind when running random software you download from the Net.

http://www.clamxav.com/

FileSpot -- Spotlight is nice, but FileSpot takes it to another level.

http://mac.synthesisstudios.com/mac/filespot/about

GimmeSomeTune -- integrates with iTunes and pulls/updates album art and lyrics, and works with Growl. Updates iChat status and images based on what you're listening to. Sweet.

http://www.eternalstorms.at/gimmesometune/

HighLight -- Instantly add file(s) or folders to your Spotlight search index.

http://homepage.mac.com/superpixel/highlight/

SimpleComic -- a great comic PDF viewer.

http://dancingtortoise.com/simplecomic/

TED -- This program scours the usual suspects for new TV episodes and integrates with your favorite Torrent program to automatically download them!

http://www.ted.nu/

DropBox -- 2GB of free, sync'ed cloud storage for your Mac (or PC/Linux box). Incredible in conjunction with 1Password.

http://www.getdropbox.com/install?os=lnx

The Unarchiver -- Ok, so you don't like Stuffit? This will pull apart almost anything.

http://wakaba.c3.cx/s/apps/unarchiver.html

Movist -- A media player based on ffmpeg/VNC that has a more polished UI than VNC.

http://code.google.com/p/movist/
VNC -- open and play anything.

Perian -- Add the ability to open and play most media formats that ffmpeg can handle inside of QuickTime.

http://perian.org/

Pixelmator -- who needs Photoshop? This $50 application is the bees knees. Cool UI, great features.

http://www.pixelmator.com/

doubleTwist -- Part media manager, part file conversion utility. If you need those TV shows on your PSP, this can handle it. Notably, doesn't support iPhone (yet).

http://www.doubletwist.com/dt/Home/Index.dt

MPlayer OSX Extended -- the benefits of Mplayer on OSX. More polished than VNC, more stable (at this point) than Movist.

http://mplayerosx.sttz.ch/

FreeDMG -- The ability to create Disk Images/.dmg files.

http://www.kelleycomputing.net/freedmg/

Tweetie -- The newest and most controversial OSX Twitter program.

http://www.atebits.com/tweetie-mac/

Boxee -- a "10 foot interface" for managing your media and Internet content sources such as Hulu.

http://www.atebits.com/tweetie-mac/

SuperDuper -- quickly and easily clone your HFS drives.

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription...

iWork 09 -- Pages is what Powerpoint will never be -- Fun.

http://www.apple.com/iwork/