Having recently made the transition to an all Macintosh household, I decided to compile this list of must haves to help my buddy Matt along:

Development:

Xcode 2.3 - Free download from Apple, it provides gcc, Interface Builder, and most of the basic GNU essentials.

iTerm - Terminal.app replacement. More feature rich, supports multiple windows and tabs, etc, etc.

TextMate - Slick lightweight text editor with features supporting every language under the sun. Customizability is its killer feature. It supports user-supplied bundle commands that allow the user to add features by scripting in their preferred language.

Python 2.4.3 - A lot of cool Mac-only Python packages are out there! Be sure to install the Universal 2.4.3 package from pythonmac.org.

ipython - Slick enhanced shell for the Python interpreter. (Requires the GNU readline library.)

Appscript - Python to Applescript bridge makes Mac scripting a breeze.

matplotlib - Matlab-like plotting package. Produce real plots without dirtying your hands on MS Excel.

Multimedia:

Handbrake - Very nice DVD => MPEG4 converter

iSquint - For making iPod video friendly movies.

MPlayer OSX - Plays just about anything.

VLC - For when MPlayer flakes out inexplicably. (Yay)

Net:

Bittorrent - Can’t live without it.

NetNewsWire - Sweet RSS/Atom fat client.

Adium - nice iChat replacement.

Fun:

Netflix Freak - Netflix fat client.

tickr for Flickr - scrolling picture collage on demand.

Compatibility:

Parallels - Cheap new VMWare competitor that allows you to run Windows in a box. That’s preferable to Boot Camp, if you ask me. Plus, this one is a real hit with wives and girlfriends because your Windows box can be removed to a closet.

Keynote - Powerpoint killer. Make killer presentations just like Jobs, and export to PPT for the losers at your job.